Reduced ultraviolet radiation transmitting, electrochromic glazing assembly

ABSTRACT

An electrochromic glazing assembly with reduced ultraviolet (UV) radiation transmission may include at least a pair of glass panels or other elements confining an electrochromic medium therebetween. Ultraviolet radiation reducing element or material are incorporated for reducing ultraviolet radiation transmission through the assembly. The ultraviolet radiation reducing element or material comprises at least one of an ultraviolet absorber, an ultraviolet absorbing polymer, and an ultraviolet absorbing glass.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior pending application Ser. No.09/418,525, filed Oct. 14, 1999, now issued as U.S. Pat. No. 6,122,093,which is a continuation of prior pending application Ser. No.09/233,164, filed Jan. 18, 1999, now issued as U.S. Pat. No. 5,986,797,which is a continuation of prior pending application Ser. No.08/939,854, filed Sep. 29, 1997, now issued as U.S. Pat. No. 5,864,419,which is a continuation of Ser. No. 08/617,333, filed Mar. 18, 1996, nowissued as U.S. Pat. No. 5,680,245, which is a continuation of priorpending application Ser. No. 08/293,736, filed Aug. 19, 1994, now U.S.Pat. No. 5,523,877, which is a continuation of prior pending applicationSer. No. 08/082,882, filed Jun. 25, 1993, now issued as U.S. Pat. No.5,355,245, which is a continuation of prior pending application Ser. No.07/732,572, filed Jul. 18, 1991, now issued as U.S. Pat. No. 5,239,406,which is a continuation-in-part of prior pending application Ser. No.07/464,888, filed Jan. 16, 1990, now issued as U.S. Pat. No. 5,115,346,which is a continuation-in-part of prior pending application Ser. No.07/155,256, filed Feb. 12, 1988, now abandoned, the disclosures of allof which are hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

This invention relates to electro-optic devices for vehicles and, moreparticularly, to an enhanced vehicular rearview mirror or window glazingincorporating an electro-optic medium allowing variation in thetransmission of light in response to application of an electric field tothe electro-optic medium.

Specifically, in one aspect, the invention is a variable reflectance,electro-optic mirror including protection against laceration injuriesand scattering of glass or other fragments if broken or damaged, againstdegradation from ultraviolet radiation, and against fogging and mistingin high humidity conditions.

This invention also relates to glazing in vehicles and, moreparticularly, to an enhanced vehicular window, sun visor, shade band orsunroof incorporating an electrochromic medium allowing variation in thelight transmitted by the glazing in response to application of anelectric field to the electrochromic medium. Specifically, the inventionis a variable transmission, electrochromic vehicular window includingprotection against laceration injuries and scattering of glass, otherfragments, or chemicals if broken or damaged, against degradation fromultraviolet radiation, and including thin film means to reflect asubstantial portion of incident, solar, near-infrared radiation.optionally, and preferably, the electrochromic glazing assembly is blueor green in transmission, as viewed from the vehicle interior, so as toreduce glare from the sun and to optimize visibility and atrue-to-nature blue view of the sky.

In a collision, the glass typically used as the substrate in vehicularrearview mirrors poses potential hazards to the driver or other vehicleoccupants. Since glass easily shatters into sharp, irregular fragments,there is a high likelihood of facial or other injury, typicallylacerative in nature, in any collision. For this reason, prior knowninterior and exterior vehicular rearview mirrors, which typicallyconsist of a single glass piece coated with reflective material, areconventionally protected by applying a tape or a plastisol-type plasticadhesive to the back surface of the glass piece. Accordingly, ifimpacted or broken in an accident, and shattered, glass fragments areretained by the tape or plastisol-type plastic adhesive.

More recently, however, a new generation of electro-optical mirrors hasemerged which are fabricated using two pieces of glass separated by agap or space which contains an electro-optic medium allowing variationin the light reflected by the assembly. For example, in liquid crystalrearview mirrors, the space between the transparent front and reflectivecoated rear glass pieces is filled with a semi-viscous liquid crystalmaterial. In electrochemichromic or electrochromic mirrors, the gap orspace contains a liquid, thickened liquid, gel or semi-solid material.

In these types of electro-optic, laminated mirror assemblies,scatterproofing of the rear glass piece is relatively easy since tape orplastisol-type plastic adhesives can be applied to its rear surfacebehind the reflective coating in the conventionally known manner.However, scatterproofing the front piece of glass in such a laminatedassembly is difficult since the material used to fill the space betweenthe front and rear glass pieces is usually insufficiently viscous oradhering to retain fragments of the front glass should it shatter in acollision.

Another problem encountered with electro-optic rearview mirrors andwindows or glazing assemblies is degradation due to exposure toultraviolet radiation over the life of the mirror or glazing.Ultraviolet (UV) radiation from the sun which penetrates the earth'satmosphere has a wavelength in the range between 290 and 400 nanometers(nm) and can cause breakdown in the operational characteristics of theelectro-optical medium including chain scission, cross-linking andstimulation of chemical changes in the chemicals used to formulate theelectro-optical medium. This interferes with electronic conjugation inthe aromatic conjugated materials typically used and thus theelectro-optic activity of those materials is impaired. Moreover, themedium will often discolor taking on a yellowish tint visible in lightreflected or passing therethrough and drastically affect the usefulnessof the rearview mirror or window. Such degradation from UV solarradiation is particularly problematic in electro-optical automotivewindows which are typically exposed to the full solar radiation, oftenwhen the electro-optical medium is in its colored state.

In order to overcome ultraviolet radiation degradation in suchelectro-optic rearview mirrors and glazings, it is possible to add UVradiation absorbing materials to the electro-optic medium. However, suchUV absorbing additives, especially in higher concentrations and withbroad UV absorbance, themselves impart a yellowish tint to the materialsto which they are added. Such yellow tint is also visible in lightreflected or transmitted therethrough. Yellow is aestheticallydispleasing in many applications, and is particularly displeasing whenused in rearview mirrors. Consumer acceptance of rearview mirrors havinga yellowish tint or cast in the reflected light has been poor. Moreover,yellow mirrors are efficient reflectors of headlamp glare which itselfis yellow. Consequently, prolonged exposure to sunlight and UVradiation, or reducing UV degradation in electro-optic mirrors with UVabsorbing additives, can create negative consumer reaction andacceptance. Likewise, a yellow tint in, for example, an automotivesunroof is consumer displeasing as it detracts from the consumer'sappreciation of, and natural view of, the blue sky.

Another objective in the use of rearview mirrors is the matching ofhuman sight sensitivity in various light conditions during the use ofsuch mirrors to the glare sources and ambient lighting present. It isknown that the spectral sensitivity of the human eye depends on itslight adaptation. Thus, daylight and night driving conditions creatediffering human eye sensitivities. Further, nearly all night driving isaffected by the reflection of light from the headlights of the driver'sown vehicle on the road. The electro-optic mirror assemblies of thisinvention should, therefore, optimally be constructed to correspond asmuch as possible with the eye sensitivities in both day and nightdriving conditions.

The electro-optic media commonly used in electro-optic mirrors andwindows are often constituted of materials and chemicals of a potentialtoxic or otherwise hazardous nature. Should the mirror glass break in anaccident, there is a possibility of automobile occupants contacting theelectro-optic media, either directly or by contact with glass particlesto which these potentially hazardous media are still adhering. Suncontact presents a hazard to the occupants through toxic effects, andthrough skin irritation such as to eyes and facial areas. Theanti-lacerative layers and laminate interlayers of this invention offera barrier that ensures that contact with chemicals used within themirror is minimized should the glass shatter in an accident.

Yet another problem is unwanted misting or fogging of the rearviewmirror surface or the glazing surface when the vehicle encounters highhumidity conditions. For example, in damp, cold conditions where theinterior passenger compartment of a vehicle has a highly humidatmosphere, water droplets may tend to condense on the rearview mirrorsurface or window surface thereby obscuring vision in the mirror orthrough the window. Not only does such condensation prevent effectiveuse of the mirror or window, but also requires frequent wiping by thevehicle driver which distracts his attention from driving.

Vehicular windows provide a field of view so that the driver can makesafe driving decisions and allow occupants to comfortably view thesurroundings. Glass vehicular sunroofs are luxury items that serve bothaesthetic and functional needs. A transparent sunroof is primarilyconsumer-selected so that the occupants feel less claustrophobic andmore linked to the outside environment. Sunroofs have a functionalbenefit in that, when opened, they can greatly increase cabinventilation and so substitute somewhat for air-conditioning.

As reviewed in the publication SMART WINDOWS FOR AUTOMOBILES by Niall R.Lynam, SAE paper #900419, Society of Automotive Engineers, InternationalCongress and Exposition, Detroit, Mich., Feb. 16-Mar. 2, 1990, thedisclosure of which is hereby incorporated by reference, increases inthe area of windows used in automobiles coupled with down-sizing ofvehicular air-conditioners and environmental concerns associated withuse of halocarbons in air-conditioners, have led to an increased need touse solar heat-load reducing glazing in vehicles. Since solar energy(for solar mass 2) is, on the average, 3% ultraviolet (UV), 48% visibleradiation, and 49% near-infrared (NIR) radiation, nearly one-half of thesolar energy can be eliminated without any loss in visibility.

Solar-energy reducing glazing is already in use on automobile windowsand is based on two principles: modification of the glass composition toincrease the infrared absorption; and deposition of single andmultilayer coatings to reflect or absorb infrared radiation. In avehicle, the glazing need not be concerned with heat insulativeproperties such as are required for solar efficient windows in buildingsand homes. Building solar windows allow as much of the solar spectrum asis possible to transmit into the room but also trap this solar energy byacting as a heat mirror for energy radiated from walls, floors,furniture, etc.

With respect to a vehicle, heat built up when parked or driven in sunnyclimates is the principal concern. Thus, the solar glazing used invehicles should, ideally, reflect away all of the incident near-IR solarradiation above around 800 nm since visible light is between about 400and 800 nm. Even with such reflection, however, the approximate 50% ofsolar energy contained in the UV/visible spectral region, iftransmitted, can contribute to heat buildup within the vehicular cabin.

Chromogenic materials have been suggested for providing electricallyvariable control over solar transmission in automobile windows. SAEpaper #900419 discloses a variety of possible designs and constructions,among them being designs using liquid crystal or electrochromicmaterials. Liquid crystal designs, and particularly those that operateby scattering light rather than by absorbing/reflecting light, however,yield only moderate solar energy benefit when used in automobileglazing. Electrochromic windows, because they do not operate by a lightscattering mechanism, are preferred for use in variable transmissionsolar-efficient automobile window glazing.

A wide variety of infrared attenuating means including those thatoperate principally by reflecting varying amounts of the near-IR region,or by absorption, also have been disclosed in the prior art. Some havebeen used in association with variable transmission liquid crystalpanels. For example, U.S. Pat. No. 4,749,261 to McLaughlin et al.describes a liquid crystal material operable to modulate lighttransmitted through a panel such as a sunroof, window, or partition. Theliquid crystal material selectively operates to transmit or to scatterlight.

McLaughlin et al. describe an embodiment which includes an infraredlight reflective material which may take the form of a stainless steelor tin oxide, optically transparent, infrared reflecting, andelectrically conductive coating that preferentially reflects infraredlight while allowing visible radiation to pass. McLaughlin et al.,however, fail to explicitly distinguish to which portion of the infraredspectrum (i.e., near-IR between 800 nm and 2500 nm or IR above 2500 nm)their invention is directed, and fail to combine that revelation with anelectrochromic medium. Other references have failed to distinguish theparticular needs of vehicular variable transmission glazing fromvariable transmission glazing usable as building windows and the like.

Accordingly, a need is apparent for a laminate electro-optic vehicularrearview mirror and glazing assembly which can be effectivelyscatterproofed to retain glass fragments from both glass pieces in theassembly, protected against lacerative-type injuries, protected againstultraviolet radiation damage throughout its life, and protected againstannoying fogging and misting of the interior cabin surface in highhumidity conditions. In addition, there is a related need forelectro-optic rearview mirror assemblies which provide reflected lightof a commercially and consumer acceptable color or tint and which matchhuman sight sensitivity in both day and night conditions to the glaresources and ambient lighting present.

In addition, a further need is apparent for a combination near-infraredattenuating/electrochromic window which maximizes solar attenuatingperformance while allowing maximum variability of visible light. Thereis also a related need for a vehicular window which combines anelectrochromic medium which attenuates visible light by absorbanceand/or reflection with an efficient near-infrared reflector and anultraviolet reducing means. Further, there is a related need for a solarattenuating window which can be effectively scatterproofed to retainglass fragments from the glass pieces in the window, protected againstlacerative-type injuries, protected against leakage of chemicals,protected against ultraviolet radiation damage throughout its life, andprotected against annoying fogging and misting of its surface in highhumidity conditions.

SUMMARY OF THE INVENTION

The present invention overcomes the above problems by providing alaminate electro-optic vehicular rearview mirror which is protectedagainst scattering of glass or other mirror element fragments if brokenor damaged in a collision while reducing the risk of laceration fromcontact with the front glass or other element. In addition, the assemblyis protected against degradation by ultraviolet radiation. Theultraviolet radiation reduction may be incorporated together with thescatterproofing, anti-lacerative protection. Further, the assembly mayincorporate anti-fogging/anti-misting materials which prevent or reducecondensation and fogging in high humidity conditions.

In one form, the invention is an anti-lacerative, scatter protected,laminate, electro-optic rearview mirror assembly including first andsecond spaced optically transparent elements mounted in a mirror case.The elements each have front and rear surfaces defining a space betweenthe rear surface of the first element and the front surface of thesecond element. An electro-optic medium is included in the space and hasa light transmittance variable upon application of an electric field.Means are provided for applying an electric field to the electro-opticmedium to cause variation in the light transmittance thereof. Areflective coating is included on one surface of the second element andis adapted to reflect light incident thereon through the first elementand the electro-optic medium. A layer of optically transparent,tear/perforation resistant material is adhered to the front surface ofthe first element for retaining and preventing scattering of fragmentsfrom that element in the event of damage or breakage and for reducingrisk of laceration from contact with the first element if damaged orbroken.

The optical elements may be glass or plastic. The anti-lacerative,anti-scattering layer preferably is a sheet of polymer material such asreticulated polyurethane. In order to reduce ultraviolet radiationtransmitted into the assembly, the polymer may be a combination ofpolyvinylbutyral and polyester which has ultraviolet radiation reducingproperties. Alternately, the anti-lacerative layer may incorporateultraviolet radiation absorbing, blocking or screening additivesselected from the group including benzophenones, cinnamic acidderivatives, esters of benzoin acids, salicylic acid, terephthalic andisophthalic acids with resorcinol and phenols, pentamethyl piperidinederivatives, salicylates, benzotriazoles, cyanoacrylates, benzilidenes,malonates and oxalanilides which may also be combined with nickelchelates and hindered amines. These additives also stabilize theanti-lacerative layer itself against ultraviolet degradation.

Another UV radiation reducing alternative is the use of a clear,transparent UV transmission reducing coating preferably applied to thefront surface of the front glass element followed by theanti-lacerative, scatterproofing polymer layer.

It is also possible to incorporate a sheet polarizer with theanti-lacerative layer, or apply a dichroic, reflective filter materialto the glass element which provides wide band ultraviolet radiationreduction. Examples of such filters include thin film stacks.

It is also possible to substitute a laminated glass assembly for thefront element, such assembly including a pair of glass panels adhered toone another with a sheet of polyvinylbutyral or sheet polarizer whichhave ultraviolet radiation reducing qualities. An anti-lacerative layermay be applied to the front surface of the first of the two glass panelsin such a laminate.

A second form of the invention is a reduced ultraviolet radiationtransmitting laminate electro-optic rearview mirror assembly which alsoincludes first and second spaced optically transparent elements, anelectro-optic medium therebetween, means for applying an electric fieldto the electro-optic medium and a reflective coating on one surface ofthe second element. In this form, ultraviolet radiation reducing meansare incorporated in the assembly for reducing transmission ofultraviolet radiation into the electro-optic medium and the assembly.

Preferably, such ultraviolet radiation reducing means may include glasshaving an increased iron oxide or cerium oxide content or otherspecialized glasses such as blue or green tinted glass which are highlytransmitting in the visible portion of the electromagnetic spectrum buthave greatly reduced transmission in the ultraviolet portion of theelectromagnetic spectrum. Anti-lacerative layers may be adhered to thefront surface of such UV reducing glass to both strengthen the glass andprovide anti-lacerative, scatterproofing properties. When suchanti-lacerative layers are used, similar UV absorbers, blockers andscreening materials may be incorporated in such layer. Alternately,sheet polarizers, transparent, UV reducing coatings, and UV radiationdichroic reflective filter materials may be used or added. Anti-foggingadditives may also be included.

In addition, the ultraviolet radiation reducing means may include alaminated assembly incorporated as the front or first element of themirror assembly and include spectrally selective absorbing means forabsorbing more light in those regions of the visible spectrum from about560 nanometers to about 780 nanometers than is absorbed in those regionsof the visible spectrum from about 400 nanometers to about 560nanometers. Such spectrally selective absorbing means may include blueor green tinted specialized glass or blue or blue/green tinted polymericinterlayers adhering the panels of the laminate front element together.In addition, coatings or layers of UV radiation reducing paint orlacquer or polymeric films may be included on the interior, facingsurfaces of the laminate. Alternately, the panels of the laminate firstelement assembly may be adhered via a moderate to low modulus ofelasticity adhesive layer which is preferably poured between the panels,cured with ultraviolet radiation, and which preferably includes an indexof refraction similar to that of the glass panels to reduce distortion.

It is also possible to incorporate UV radiation reducing additivesdirectly in the clear plastic when such plastic is used to form thefirst optical element. Alternately, UV reducing additives can be addedto the electro-optic medium for UV stabilization.

The present invention also provides a combination near-infraredattenuating, electrochromic glazing assembly which is protected againstscattering of glass or fragments if broken or damaged in a collisionwhile reducing the risk of laceration from contact. Further, protectionis offered against contact with the chemicals used in theelectro-optical medium should the assembly be damaged in an accident. Inaddition, the window assembly is protected against degradation byultraviolet radiation. The ultraviolet radiation reduction may beincorporated together with the scatterproofing, anti-lacerativeprotection. Further, the window assembly may incorporateanti-fogging/anti-misting materials which prevent or reduce condensationand fogging in high humidity conditions.

In one form, the invention is an anti-lacerative, scatter protected,electrochromic glazing assembly including first and second spacedoptically transparent elements. The elements each have inside andoutside surfaces defining a space between the outside surface of thefirst element and the inside surface of the second element. Anelectrochromic medium is included in the space and has a lighttransmittance variable upon application of an electric field. Means areprovided for applying an electric field to the electrochromic medium tocause variation in the light transmittance thereof. Near-infraredreflective means are located on at least one of the first and secondelements for reducing the transmission of near-infrared radiationthrough said window assembly. The reflective means incorporate at leastone semi-transparent, elemental, thin metal film which reflects at leastabout 30% of the solar energy for Air Mass 2 in the spectral region from800 nanometers to 2500 nanometers. In a preferred embodiment, the thinmetal film has a physical thickness of between about 80 angstroms and300 angstroms and, preferably, of sheet electrical resistance of nogreater than about 8 ohms/square.

The optical elements for the glazing assembly may be glass or plasticand may employ the same anti-lacerative, anti-scattering,absorbing/filtering, tinting and ultraviolet reducing means listed abovefor the optical elements of the electro-optic mirror. It is alsopossible to substitute a laminated glass assembly for the inside elementor the outside element, such assembly including a pair of glass panelsadhered to one another with an interlayer such as a sheet of plasticizedpolyvinylbutyral or equivalent which has ultraviolet radiation reducingqualities. An anti-lacerative layer may be applied to the inner surfaceof the first or innermost of the two glass panels where the firstelement is such a laminate.

In preferred forms, the near-infrared reflective elemental thin film issandwiched between optically transparent layers consisting of metaloxide, nitride, halide, or sulfide thin films. These thin films serve asan undercoat to the thin metal film to enhance its bonding to thesubstrate and as a visible light anti-reflection overcoat to enhancevisible light transmitivity. The elemental thin metal film is preferablyelemental silver or a silver alloy such as with copper but with thesilver being the majority component. Gold, copper, or aluminum arealternate choices.

Accordingly, the present invention recognizes and applies novelprotective concepts to laminate, electro-optic vehicular rearviewmirrors and glazings not previously obtained. The invention solves threedifficult problems encountered in prior commercialization of laminateelectrochromic mirrors, namely, scatter protecting the front glasselement, reducing lifetime ultraviolet degradation problems arising fromthe UV instability of the typical electro-optical medium sealed betweenthe glass elements, and reducing fogging or misting caused bycondensation in high humidity conditions. Further, the inventionenhances the aesthetic appearance and customer acceptance of UVstabilized, electro-optic rearview mirror assemblies which wouldotherwise reflect light with a yellow tint by absorbing light in theyellow/orange/red regions of the visible spectrum to produce acommercially acceptable silvery or silvery-blue reflection. Further, theinvention matches human sight sensitivity in both day and nightconditions for either inside or outside mirrors to the glare sources andambient lighting present by incorporating means causing light reflectionin the blue region of the visible spectrum and thus well-suiting themesopic human vision range. In addition, these results are obtained inan economical manner easily incorporated in existing rearview mirrorcases requiring no specialized supports or surrounding apparatus in thevehicle.

The present invention also recognizes that maximum solar attenuationperformance can be obtained through the combination of novelnear-infrared attenuating concepts and electrochromic concepts whilemaintaining maximum variability of visible light. The glazing assemblyincorporating the near-infrared attenuating and electrochromic meansalso incorporates the novel protective concepts listed above which solvefor glazings or windows the similar problems encountered in priorcommercialization of laminate electrochromic mirrors, namely, scatterprotection, reduction of ultraviolet instability of the typicalelectrochromic medium, and diminution of fogging or misting problems.Further, the solutions suggested for masking the yellow tint caused byultraviolet reductors are applicable to the window assembly.

These and other objects, advantages, purposes and features of theinvention will become more apparent from a study of the followingdescription taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side elevation of a scatter protected,anti-lacerative, laminate, electro-optic rearview mirror assembly of thepresent invention;

FIG. 2 is a sectional side elevation of a scatter protected,anti-lacerative and ultraviolet radiation protected, laminate,electro-optic rearview mirror assembly of the present invention;

FIG. 3 is a graph showing percent transmission of electromagneticradiation of wavelengths between 230 and 500 nanometers through a twomillimeter glass sheet coated with indium tin oxide on one surface andhaving a sheet of polyvinylbutyral/polyester composite adhered to itsopposite surface;

FIG. 4 is a graph of the percent transmission of electromagneticradiation of wavelengths between 230 and 500 nanometers through a twomillimeter glass sheet coated only on one surface with indium tin oxide;

FIG. 5 is a second embodiment of the scatter protected, anti-lacerativeand ultraviolet radiation protected, laminate, electro-optic rearviewmirror assembly of the present invention;

FIG. 6 is a third embodiment of the scatter protected, anti-lacerativeand ultraviolet radiation protected, laminate, electro-optic rearviewmirror assembly of the present invention;

FIG. 7 is a fourth embodiment of the scatter protected, anti-lacerativeand ultraviolet radiation protected, laminate, electro-optic rearviewmirror assembly of the present invention;

FIG. 8 is an ultraviolet radiation protected, laminate, electro-opticrearview mirror assembly of the present invention;

FIG. 9 is a second embodiment of an ultraviolet radiation protected,laminate, electro-optic rearview mirror assembly of the presentinvention;

FIG. 10 is a scatter protected, anti-lacerative, anti-fogging, laminate,electro-optic rearview mirror assembly;

FIG. 11 is a graph showing percent transmission of electromagneticradiation through a one millimeter glass sheet coated with indium tinoxide on one surface and a coating of clear acrylic including CYASORB™UV radiation reducing compounds on its opposite surface;

FIG. 12 is a graph showing percent transmission of electromagneticradiation through a one millimeter glass sheet coated with indium tinoxide on one surface and a coating of clear acrylic on its oppositesurface;

FIG. 13 is a graph showing percent transmission of electromagneticradiation through a one millimeter glass sheet coated with indium tinoxide on one surface and clear UV protecting lacquer on its oppositesurface;

FIG. 14 is a fifth embodiment of the scatter protected, anti-lacerativeand ultraviolet radiation protected, laminate, electro-optic rearviewmirror assembly of the present invention;

FIG. 15 is a third embodiment of an ultraviolet radiation protected,laminate, electro-optic rearview mirror assembly of the presentinvention;

FIG. 16 is a sixth embodiment of the scatter protected, anti-lacerative,ultraviolet radiation protected, laminate, electro-optic rearview mirrorassembly of the present invention;

FIG. 17 is a graph showing the solar spectrum in the ultraviolet regionincident at a desert location such as Tucson, Ariz.;

FIGS. 18a and 18 b are graphs showing the percent light transmission of0.063 inch thick, standard, clear, soda lime glass in the ultravioletand visible regions of the spectrum, respectively;

FIG. 19 is a graph showing the solar radiation in the ultraviolet regiontransmitted by 0.63 inch thick, standard, clear, soda lime glass;

FIG. 20 is a graph showing the percent light transmission of specificsolutions of four cathodic electrochemichromic compounds includingmethylviologen (MV), ethylviologen (EV), benzylviologen (BV) andheptylviologen (HV) in the ultraviolet region of the spectrum;

FIG. 21 is a graph showing the percent light transmission of specificsolutions of four anodic electrochemichromic compounds includingdimethyldihydrophenazine (DMPA), diethyldihydrophenazine (DEPA),tetramethylphenylenediamine (TMPD), and tetratetramethylbenzidine (TMBZ)as well as thiafulvalene in the ultraviolet region of the spectrum;

FIGS. 22a and 22 b are graphs showing the percent light transmission ofSOLEXTRA 7010™ blue tinted specialized glass in the ultraviolet andvisible regions of the spectrum, respectively;

FIGS. 23a and 23 b are graphs showing the percent light transmission ofSUNGLAS™ Blue blue tinted specialized glass in the ultraviolet andvisible regions of the spectrum, respectively;

FIG. 24 is a graph showing the relative spectral power of StandardIlluminant Sources A and C as well as the main color bands of thevisible spectrum;

FIG. 25 is a graph showing the dark/scotopic and bright/photopicsensitivity of the human eye superimposed on the spectral output of atungsten lamp used as Standard Illuminant A;

FIGS. 26a and 26 b are graphs showing the percent light transmission ofSUNGLAS™ Green green tinted specialized glass in the ultraviolet andvisible regions of the spectrum, respectively;

FIGS. 27a and 27 b are graphs showing the percent light transmission ofa pair of clear soda lime glass panels laminated together by SAFLEX™SR#11 polyvinylbutyral sheeting in the ultraviolet and visible regionsof the spectrum, respectively;

FIGS. 28a and 28 b are graphs showing the percent light transmission ofBUTACITE™ Cobalt Blue polymeric interlayer sheeting laminated betweentwo clear soda lime glass panels in the ultraviolet and visible regionsof the spectrum, respectively;

FIGS. 29a and 29 b are graphs showing the percent light transmission ofa pair of clear soda lime glass panels laminated by SAFLEX™ Blue Green377300 polyvinylbutyral sheeting in the ultraviolet and visible regionsof the spectrum, respectively;

FIG. 30 shows the percent light transmission of conventional clear sodalime glass coated with UV absorbing PC-60 lacquer;

FIG. 31 is a graph showing the percent light transmission of clear sodalime glass having a UV absorbing coating of ZLI-2456 lacquer;

FIG. 32 is a graph showing the percent light transmission of clear sodalime glass coated with a sheet of SCOTCHTINT™ SH2CLX clear polymericfilm;

FIG. 33 is a graph showing the percent light transmission of a 35 micronthickness coating of NORLAND NOA 65™ ultraviolet cured epoxy adhesive onclear soda lime glass;

FIG. 34 is a graph showing the percent light transmission of a 500microns thick coating of a cured mixture of 15% EPON 828™, 35% HELOXYMK107™ and 50% CAPCURE 3-800™ on clear soda lime glass;

FIGS. 35a and 35 b are graphs showing the percent light transmission ofa pair of clear soda lime glass panels laminated together by BUTACITE™14 NC-10 polyvinylbutyral sheeting in the ultraviolet and visibleregions of the spectrum, respectively;

FIG. 36 is a graph which illustrates the solar energy spectrum (for AirMass 2) constituting the solar load incident on an automobile;

FIG. 36a is a graph which illustrates the variance of percent luminoustransmission caused by varying the thickness of a silver elemental thinfilm deposited onto a soda lime glass substrate;

FIG. 36b is a graph which illustrates that the thickness of a silverelemental thin film can be increased to 300 angstroms while sustainingthe percent luminous transmission above 50%;

FIG. 37 is a sectional view of a first embodiment of the scatterprotected, anti-lacerative, ultraviolet radiation protected, laminate,electrochromic, near-infrared attenuated glazing assembly of the presentinvention;

FIG. 38 is a sectional view of a preferred thin film stack typicallyapplied to a glass surface of one of the glass elements of the presentinvention to form a specialized near-infrared reflector;

FIG. 39 is an enlarged sectional view of the near-infrared reflector ofthe present invention applied to a surface of a glass element;

FIG. 40 is a sectional view of a second embodiment of the scatterprotected, anti-lacerative, ultraviolet radiation protected, laminate,electrochromic, near-infrared attenuated glazing assembly of the presentinvention;

FIG. 41 is a graph which compares the near-infrared reflectanceperformance in the 800-2500 nm electromagnetic radiation region of thespectrum for a half-wave coating of ITO on glass, a full-wave coating ofITO on glass, and two different, commercially available heat mirrorstructures on glass;

FIG. 41A is a graph of the percent reflectance of near-infrared solarenergy for Air Mass 2 in the 800 to 2500 nanometer spectral range forsilver thin elemental films of thickness between about 60 and 400angstroms on glass;

FIG. 41B is a graph similar to FIG. 41B but with the silver elementalthin film sandwiched between two 180 angstrom thick titanium dioxidelayers on glass;

FIG. 42 is a sectional view of a third embodiment of the scatterprotected, anti-lacerative, ultraviolet radiation protected, laminate,electrochromic, near-infrared attenuated glazing assembly of the presentinvention;

FIG. 42A is a sectional view of a fourth embodiment of the scatterprotected, anti-lacerative, ultraviolet radiation protected, laminate,electrochromic, near infrared attenuated glazing assembly of the presentinvention; and

FIG. 43 is a sectional view of perimetal coatings which can be appliedto the scatter protected, anti-lacerative, ultraviolet radiationprotected, laminate, electrochromic, near-infrared attenuated glazingassemblies of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS ELECTRO-OPTIC REARVIEW MIRRORDEVICES

Referring now to the drawings in greater detail, FIG. 1 illustrates alaminate, electro-optic rearview mirror assembly 10 having a frontelement 12 which is scatter and anti-lacerative protected with aresinous, polymeric or other coated or applied layer 14 on its first orfront surface 11. Element 12 is preferably formed from a generallyplanar sheet of conventional soda lime window glass as is second glasselement 16 which is spaced slightly rearwardly from front glass piece 12to define a gap or space 18 for receiving an electro-optic medium 20 asexplained below. As explained hereinafter, elements 12, 16 may also beresinous, polymeric sheets to further prevent fragment scattering andlacerative injuries if broken and to reduce weight. Space 18 is formedbetween the generally parallel rear surface 13 of front glass element 12and forward facing surface 17 of rear glass element 16. Preferably, eachof the front and rear surfaces 13, 17 is coated with a layer of indiumtin oxide (ITO) which is substantially transparent to incident visiblelight yet is sufficiently electrically conductive to enable applicationof an electric field or voltage across space 18 between ITO layers 13 a,17 a. Electrical energy is provided by wire leads 22, 24 secured inconventional manner to the upper portions of ITO coatings 13 a, 17 a asshown in FIG. 1.

The rear surface 25 of rear glass element 16 is coated with a reflectivelayer 26 preferably of metallic material such as aluminum, or acombination of silver and copper as is conventionally known. Such layerprovides a highly specular surface which reflects approximately 80-90%of the light incident thereon through layer 14, front and rear glasselements 12, 16 and electro-optic medium 20 in space 18. In order toprevent scattering of glass fragments from the rear glass element 16 inthe event of breakage or damage during a collision in the vehicle, alayer 28 of tape or a plastisol-type plastic adhesive, typically about0.1 millimeters thick, is applied to the rear surface of reflectivecoating 26. Anti-scattering layer 28 may be opaque, translucent ortransparent since it is behind reflective coating 26 and need nottransmit or reflect any light.

In order to confine and retain the electro-optic medium in gap 18, aperipheral seal 29, formed from an epoxy material which adheres well tothe ITO coatings 13 a, 17 a on glass surfaces 13, 17 is applied adjacentthe periphery of glass elements 12, 16. A suitable epoxy sealingmaterial is EPON 828™ from Shell Chemical Company of Houston, Tex. curedby polyamide based curing agents such as V-40™ from Miller StephensonCompany of Danbury, Conn. The epoxy is preferably silk screened onto theinner surface of the front glass element 12 or the back glass element 16or onto both glass elements. The corresponding glass element is thenplaced face to face with the still tacky epoxy. Seal 29 is then fullycured, typically by placing the assembly into an oven at 110° C. forthree hours. Gap 18 can then be filled by a variety of means such assimple injection of electro-optically active material using a syringe orby vacuum backfilling using a technique well established for manufactureof liquid crystal devices.

Assembly 10 is preferably incorporated in a molded thermoplastic orother mirror case 30 of conventional form and supported within a vehiclein a conventionally known manner through an articulated support from theinside windshield surface or a header mounted support arm.

Typically, glass elements 12, 16 will each be two millimeters inthickness while ITO coatings 13 a, 17 a will have a typical thickness of1,500 angstroms. Reflective coating 26 may have a thickness within therange of between about 500 and 1,000 angstroms. Various types ofelectro-optic media may be inserted in gap 18. For example, a suitableliquid crystal material in which molecules are oriented to block thepassage of light therethrough when an electric field is applied is aguest host dye such as D5™ produced by BDH Co. of Dorset, Englanddissolved in n-type nematic liquid crystal such asn-(p-methoxybenzilidene)-p′-butylaniline. For such material, cell gap 18is typically 8 to 12 microns. For electrochemichromic mirrors, the gapmay contain a liquid, thickened liquid, gel or semi-solid material suchas formulations described in U.S. Pat. No. 3,806,229 to Schoot. Inelectrochromic mirrors, a material such as POLY-AMPS™ available fromLubrizol Corp. of Wickliffe, Ohio may be used. Also, a liquid, thickenedliquid, gel or semi-solid material may be used as is conventionallyknown. Cell gap or space 18 is typically 50 to 100 microns in theseelectrochromic or electrochemichromic devices. With the lattermaterials, application of an electric field will cause the media 20 tocolor to successively darker colors or shades as larger voltages areapplied. When voltage is turned off or reversed, the coloring isbleached allowing full transmittance of light and, hence, fullreflectivity from reflective layer 26.

Because the electro-optic media 20 such as those described above aretypically of relatively low viscosity and have little or no capabilityof retaining or holding solid elements thereto, the scatter andanti-lacerative protection conventionally available through the use oftape or plastisol layers such as those at 28 on rear glass element 16has been unavailable for use with the front glass element 12 becausetransmission of light through the glass element must be unimpeded. Thepresent invention overcomes that problem by providing scatterproofing,anti-lacerative layer 14 which retains fragments should glass element 12be shattered. Layer 14 also provides enhanced anti-lacerative protectionsince it remains intact upon collision, is tear and perforationresistant and thus reduces or avoids laceration injury to the skin ofany person contacting the shattered or broken mirror.

A specific example of a material found useful for layer 14 isreticulated polyurethane having a thickness within the range of about0.01 to about 0.25 inches and marketed under the trade name SECURIFLEX™by Saint-Gobain Vitrage of Paris, France. When used as layer 14,SECURIFLEX™ has excellent adhesion to glass surface 11 for retainingglass fragments during and after shattering in a collision. It also hashigh deformation capacity to resist tearing while continuing to form aprotective screen which protects the skin of any person impacting themirror and preventing contact with broken, jagged edges of the glass. Italso has excellent optical quality, clarity and transparency so as notto detract from the rear vision capability of the rearview mirror.Further, it is abrasion and scratch resistant so that high quality clearimages can be obtained in the mirror throughout its life. It is alsorelatively inert and resistant to environmental variation such as highand low temperatures, high and low humidity conditions.

Use of an anti-lacerative layer 14 also affords another advantage. It isknown that several electro-optic mirror devices developed in recentyears have generally poor ultraviolet radiation stability. When exposedto prolonged ultraviolet radiation from sunlight, such electro-opticassemblies may suffer substantial degradation of their electro-opticmedia resulting in poor electrical coloration responsiveness includingincreased response time and/or failure to properly bleach when electricvoltage is switched off. Permanent discoloration of the medium may alsooccur. This can cause substantial vision problems. An example of theultraviolet region of the solar spectrum incident at a desert locationsuch as Tucson, Ariz. is shown in FIG. 17. Such solar spectrum musttypically pass through a glass front panel of an electro-optic rearviewmirror assembly to irradiate the electro-optic solution in anelectro-optic rearview mirror assembly such as that shown in FIG. 1 orthe other assemblies shown herein. FIG. 17 shows that there is little orno incoming solar radiation below about 295 nm. The light transmissionof a 1.6 nm thick panel of standard, clear, soda lime glass is shown inFIGS. 18a and 18 b while the solar energy spectrum transmitted into anyelectro-optic medium behind such a front glass piece is the combinationof the graphs in FIGS. 17 and 18 as shown in FIG. 19. The 0.063 inch(1.6 mm) soda lime glass panel passes about 63% of the incoming UV solarenergy in the 250-350 nm region and about 90% in the 350-400 nm region.Overall, a 1.6 mm soda lime glass sheet passes about 83% of the incidentsolar energy in the 250-400 nm region. Thus, a substantial portion ofthe incoming solar UV radiation is unattenuated by the glass frontpanel.

When such solar radiation passes into the electro-optic mediumtherebehind it irradiates the electro-optic species. Electrochemichromic(ECC) materials, especially organic species, are particularlysusceptible to degradation by UV radiation. This is caused by theirabsorption of UV radiation with consequent disruption of electronicstates. As shown in the graph of FIG. 20, the cathodically coloring ECCspecies most commonly used in prior art literature such asmethylviologen (MV), ethylviologen (EV), benzylviologen (BV), andheptylviologen (HV), have an absorption peak below 295 nm and, thus, arelargely nonabsorbing to the solar UV radiation transmitted into an ECCcell. However, as shown in FIG. 21, anodic compounds, such asdimethyldihydrophenazine (DMPA), diethyldihydrophenazine (DEPA),tetramethylphenylenediamine (TMPD), and tetratetramethylbenzidine (TMBZ)as well as thiafulvalene have substantial UV radiation absorbance in the250-400 nm region. For example, DMPA in 0.0002M solution in acetonitrile(AN) and in a 1 mm pathlength quartz cell absorbs about 22% of the UVsolar energy spectrum in the 250-350 nm region. Therefore, it isdesirable to shield the ECC compounds from UV irradiation in thisregion. Also, because some absorption continues up to about 400 nm orso, and since the solar energy transmitted into the cell as shown inFIG. 19 is also substantial in the 350-400 nm region, it is beneficialto protect the ECC compounds from irradiation in this region as well.

The present invention recognizes that use of ultraviolet radiationabsorbing, blocking or screening materials, either incorporated in theanti-lacerative layer or in layers in addition to such layer, willreduce ultraviolet radiation impinging on the mirror assembly and theelectro-optic medium and significantly prolong its lifetime.

It is also recognized that substantial reduction in the amount of UVradiation transmitted into the electro-optic medium of the assembly maybe accomplished by using specialized glasses, paints/lacquers, andlaminate interlayers, coatings and/or films while simultaneously andsynergistically protecting a vehicle driver against laceration or injurydue to scattering or breaking of glass fragments should the protectedmirror assembly be struck in an accident.

As shown in FIG. 2, an enhanced, laminate, electro-optic rearview mirrorassembly 35 with increased ultraviolet radiation resistance andstabilization is shown. As with subsequent embodiments of the inventionexplained below, assembly 35 is similar to the mirror assembly 10 ofFIG. 1 but includes a different scatter protecting, anti-lacerative, UVradiation reducing layer 36 on the front surface of glass element 12.Layer 36 is preferably of two-ply construction comprising a laminate ofpolyvinylbutyral and polyester commercially available from E. I. duPontde Nemours and Company under Product No. duPont BE1028D and also has thesame qualities as described for polyurethane layer 14. The outer ply orlayer 40 is abrasion resistant, weather resistant, polyester while theinner ply or layer 38 is resilient, tear resistant polyvinylbutyral.Composite layer 36 has a thickness preferably between about 0.005 and0.25 inches, and provides a solution to two problems found duringcommercialization of prior known laminate electro-optic, and especiallyelectrochromic mirrors, i.e., difficulty in scatter protecting the frontglass element 12 and protection against degradation of the electro-opticor electrochromic media 20 in space 18 throughout the lifetime of theassembly due to inherent ultraviolet radiation instability andsensitivity.

The polyester/polyvinylbutyral composite layer 36 is a particularly goodfilter for ultraviolet radiation as shown in FIGS. 3 and 4. FIG. 3 is agraph of the percent transmission of electromagnetic radiation through atwo millimeter thick element of conventional soda lime window glasscoated with a layer of indium tin oxide (ITO) on one surface and a layerof duPont BE1028D polyvinylbutyral/ polyester composite on the oppositesurface. The graph shows the transmission over the wavelength spectrumbetween 230 and 500 nanometers (nm) and illustrates that below about350-360 nm, wavelength transmission is cut off or stopped. Ultravioletradiation which penetrates the earth's atmosphere from the sun typicallyranges in wavelength over a wide band of between about 290 and 400nanometers (nm). In contrast, light sensitive to the human eye rangesfrom about 400 nm to about 700 nm. Hence, the compositepolyvinylbutyral/polyester layer 36 substantially eliminates ultravioletradiation below about 350 nm while simultaneously scatter protecting andprotecting against laceration when applied to the mirror glass surface.

Compare the graph in FIG. 3 to that in FIG. 4 which illustrates a twomillimeter glass element coated only on one surface with indium tinoxide and not including a polyvinylbutyral/polyester layer. Such ITOcoated glass transmits light in the visible wavelength spectrum aboveabout 400 nanometers but also allows transmission of ultravioletwavelengths down to about 295 nm which is substantially farther into theUV region than with the coated glass having the two-ply composite layer36 thereon as shown in FIG. 3. Hence, reduction of UV radiationintensity passing through front glass 12 of such laminate mirrors as inassembly 35 substantially increases the useful lifetime of the mirrorassembly.

A specific example of an assembly such as that shown at 35 comprising alaminate electrochromic mirror and providing the anti-lacerative,anti-scatter, UV radiation reducing advantages of the present inventionwas fabricated consisting of two plates of ITO coated, conventional sodalime window glass separated by a gap of 50 microns. The space betweenthe two glass elements was filled with an electrochromic solutionconsisting of N,N,N′,N′ tetramethyl-1,4-phenylenediamine 0.025M,1,1′-diheptyl-4,4′-bipyridinium dibromide 0.025M and tetrabutylammoniumfluoroborate 0.5M dissolved in propylene carbonate. The nonmirroredfront glass piece was anti-lacerative protected with a duPont BE1028Dtwo-ply, anti-lacerative layer consisting of an outer abrasion resistantlayer of polyester and an inner layer of polyvinylbutyral as describedabove in connection with FIG. 2. Reflective coated, rear glass plate 16was scatter protected on its rear surface using conventional tape. Theassembly was shattered by dropping a one kg weight over a distance ofone meter to impinge on the front nonmirrored glass element, theanti-lacerative layer retained glass fragments from the front glass andremained unperforated such that it would have provided anti-lacerativeprotection if struck by a person in an accident. Moreover, when thislaminate electrochromic mirror assembly was placed under UV lamps in asunlight simulator, electrochromic activity and general mirrorperformance was maintained for a period of some five (5) times longerthan that obtained using a control sample which was similarly testedwith UV radiation but was not anti-laceratively protected with apolyester/polyvinylbutyral layer.

Although the anti-scattering, anti-lacerative layer 14 of assembly 10 inFIG. 1 provides some ultraviolet radiation reduction protection, and isitself ultraviolet radiation stable, the polyvinylbutyral/polyestercomposite is preferred since the polyvinylbutyral ply or layer hassignificantly higher UV radiation reduction capability as well asinherent UV stability than does polyurethane.

Longer lifetimes for laminate electro-optic rearview mirror assembliescan be achieved by using ultraviolet radiation absorbing, blocking orscreening materials added to or incorporated with the anti-scatter,anti-lacerative layers 14, 36 as shown in FIGS. 1 and 2. Most commercialpolymers absorb ultraviolet radiation because they possess chromophoricgroups either as regular constituents or as impurities. Only thosechromophores which absorb electromagnetic radiation of a wavelengthbelow about 400 nanometers are, therefore, effective screens against UVradiation. Polycarbonate, polyester and aromatic polyurethanes containsuch chromophores as a major part of their structures. However,polyolefins contain only relatively insignificant amounts of thesechromophores as impurities. Yet, these above materials do not absorb UVradiation uniformly over the entire UV range. The chromophores which doabsorb UV radiation can be conjugated structures, carbonyl groups,aromatic repeat units and heterocyclic repeat units. In addition, ifpolymers are used as UV screeners, they themselves must be stabilizedagainst UV radiation since UV absorption generates free radicals whichlead to chain scission and cross-linking and creation of otherstructures in these polymers. Thus, UV radiation itself degrades thepolymer material which is intended to provide a UV absorber, block orscreen by making the polymer brittle and even imparting color in thevisible region.

The addition of UV absorbing, blocking or screening additives topolymers such as the polyurethane and/or polyvinylbutyral/polyestercomposite layers 14, 36 makes these materials more efficient UVscreeners and preserves their properties over a longer period of time.Such UV additives, known as stabilizers, are transparent in the visibleregion and work to absorb UV radiation, quench the free radicals whichare generated in the polymer and prevent oxidation reactions which leadto polymer degradation. For example, UV stabilizing additives drawn frombenzophenones, cinnamic acid derivatives, esters of benzoin acids,salicylic acid, terephthalic and isophthalic acids with resorcinol andphenols, pentamethyl piperidine derivatives, salicylates,benzotriazoles, cyanoacrylates, benzilidenes, malonates and oxalanilidesare effective to block UV radiation and stabilize the polymer layer whenimpregnated in such layer, included in separate coatings in addition tosuch layer or incorporated directly in front element 12 such as when itis cast from plastic. Other additives may be combined with the abovematerials such as nickel chelates and/or hindered amines. The followingtable shows several combinations of commercially available polymers andUV additives which may be used:

Polymer Stabilizer Polyolefins 2-hydroxy-4-octoxybenzophenones nickelchelates hindered amines Styrenics hindered amines2-hydroxyphenylbenzotriazole PVC benzotriazoles benzophenonesacrylonitriles Unsaturated Polyesters 2-hydroxybenzotriazolebenzophenone Polyurethanes benzotriazole pentamethyl piperidinederivatives Polycarbonate 2-hydroxy-phenylbenzotriazole Polyamidestetramethyl piperidyl sebacate Acrylic 2-hydroxyphenylbenzotriazole

In many instances, two or more of such additives are combined togetherfor increased, synergistic effects in UV radiation reduction andstabilization.

UV stabilizers/blockers/filters/absorbers are incorporated directly intothe polymer anti-lacerative layer(s) 14, 36 in a variety of ways. Forpolyvinylbutyral, UV blocking additives are compounded with the PVBresin. Alternately, the UV blockers are dissolved in plasticizers whichare then used to plasticize the PVB. PVB can also be dissolved in asuitable solvent, with UV stabilizers next added to the PVB solution anda UV stabilized PVB film/sheet can be cast from this solution. UVblockers can also be incorporated into polyester either throughcompounding or by solvent casting. Polyurethane anti-lacerative sheetingis a thermoset usually formed from reaction of isocyanate and polyols.Since both of these starting materials are liquids, UVblocker/stabilizers/filters/absorbers can be added to either theisocyanate component or the polyol component or to both. Concentrationsof the various additives for combination with the various polymers areconventionally known such as are disclosed in U.S. Pat. No. 4,657,796 toMusil et al.

As an alternative, UV blockers, filters or screens, or absorbers may becoated directly onto the front element 12, preferably on the firstsurface 11, regardless of whether it is glass or plastic (see FIG. 9). Aclear transparent coating packed with UV blockers/filters/ absorbers maybe cast, spun, dipped, brushed, painted or sprayed onto glass surfacesthrough which UV radiation must pass before reaching theelectro-optically active medium. A suitable solution can be made bydissolving a clear thermoplastic acrylic, polystyrene, NAS (70%polystyrene; 30% acrylic copolymer), polycarbonate, TPX(polymethylpentene), or SAN (styrene acrylonitrile copolymer) in asuitable solvent such as acetone, ethyl acetate, acetonitrile,tetrahydrofuran or any other common volatile solvent. To this, UVblockers are added such as CYASORB™ UV1084 or UV5411, available fromAmerican Cyanamid of Stamford, Conn., or any suitable material drawnfrom known UV blockers up to concentrations close to their solubilitylimit. CYASORB™ UV5411 is a benzotriazole while CYASORB™ UV1084 is anorgano-nickel complex or nickel chelate. The solution so constituted canthan be cast, spun, sprayed, brushed, painted or dipped onto, forinstance, the outer surface of front glass element 12 followed byapplication of anti-lacerative layer 14 or 36 either with or without UVreducing additives as described above.

For example, a 2.5% weight/volume casting solution was prepared bydissolving commercial acrylic sheeting in a 50:50 mixture of acetone andtoluene. To 100 mls of this acrylic solution, 1.6 g of CYASORB™ UV1084and 1.89 g of CYASORB™ UV5411 were added. When cast onto a piece of onemm thick ITO coated glass in a thickness of about eight microns, theacrylic was UV stabilized and yielded the transmission spectrum shown inFIG. 11. Transmission through such coated glass in the region from about280 nm to about 350 nm was markedly reduced compared to similartransmission spectra generated when only a 2.5% non-UV stabilizedacrylic solution was cast onto ITO coated glass (FIG. 12) or when noacrylic was cast and a spectrum of ITO coated glass itself was generated(FIG. 4). In spite of low UV transmission, the UV stabilized castacrylic coating was highly transparent in the visible portion of theelectromagnetic spectrum.

Alternatively, UV stabilizers/blockers/filters/ absorbers can beincorporated into the polysiloxane solutions, such as Dow Corning ARC™coatings, available from Dow Corning Inc. of Midland, Mich. These arecommonly available to impart a transparent anti-abrasion coating ontooptical plastics which can be used for front element 12 to furtherreduce fragment scattering and laceration-type injuries. Alternately, UVstabilizers/ absorbers/blockers/filters can be added to thermosettingoptical plastics such as CR-39™ (allyl diglycol carbonate) or opticalnylons or polysulfones. With thermosetting materials such as CR-39™optical plastic, available from PPG Industries, Inc. of Pittsburgh, Pa.,the UV absorbing, blocking or screening additive is incorporated in theinitial plastic components and cast onto the front surface of frontelement 12 prior to assembly followed by suitable curing in theconventionally known manner.

If a UV absorbing/blocking/screening material such as CR-39™ above iscast as a separate sheet, it may then be mounted on and adhered to frontsurface 11 of a clear plastic front element 12 with an adhesive bondingsubstance such as VERSILOK™ acrylics available from Lord Corporation ofErie, Pa. In such case a UV reducing additive such as benzotriazoles orhindered amines can also be incorporated directly in the adhesivebonding agent. Alternately, the sheet may be press laminated to thesurface under increased pressure and modest heat.

As an alternative to adding the UV reducing additive materials to thescatter preventing, anti-lacerative layers 14, 36 or other polymers, oras coatings in combination with such anti-lacerative layers, or ascoatings in combination with the addition of the above mentioned typesof additives to such layers, other materials may be used to decrease theultraviolet radiation passing through the front element 12 to theinterior of the mirror assemblies as shown in FIGS. 5-10.

In FIG. 5, where like numerals indicate like parts to those describedabove, a laminate, electro-optic rearview mirror assembly 45 has frontglass 12 replaced with a laminate glass assembly comprised of a frontglass element 12 a having parallel front and rear surfaces adhered to anintermediate glass element 12 b also having parallel surfaces by aninterlayer 12 c of polyvinylbutyral (PVB). Layer 12 c is adhered to therear surface of glass element 12 a and the front surface of glasselement 12 b by heat and pressure lamination such as with theconventionally known autoclave method or the like. Glass elements 12 a,12 b may be conventional soda lime window glass. The rear surface ofglass element 12 b is coated with indium tin oxide layer 13 which is, inturn, sealed with the front ITO coated surface of rear glass element 16by seal 29 to provide the space 18. A scatter preventing,anti-lacerative, ultraviolet radiation reducing layer such as that shownabove at 14 or 36 may be adhered to the front surface of front glasselement 12 a by suitable adhesives, heat, pressure or curing to providethe additional advantages noted above. However, the laminate glassassembly of assembly 45 inherently affords extra safety advantages bycontributing to the reduction of ultraviolet radiation transmission intothe assembly and providing greater shatter resistant strength for theassembly while providing scatter protection due to the use of the PVBlayer 12 c together with the anti-lacerative protection of layers 14 or36.

With reference to FIGS. 6 and 7, where like numerals indicate likeparts, it is also possible to incorporate sheet polarizers in the mirrorassembly to further prevent ultraviolet radiation transmission into theassembly. In FIG. 6, a laminate electro-optic rearview mirror assembly50 includes a layer of light polarizing sheet material 52 applied to thefront surface 11 of front glass element 12 prior to adherence of theanti-scatter, anti-lacerative layer 14 or 36 mentioned above. A suitableH-sheet polarizer material is that sold under Product No. HN-38 byPolaroid Corporation of Cambridge, Mass. Such sheet polarizers act toblock and screen out ultraviolet radiation below wavelengths of about380 nm.

Alternately, a sheet polarizer material 57 like that above may beincorporated in the laminate electro-optic rearview mirror assembly 55of FIG. 7 where it is laminated and adhered as an interlayer between thefront and rear surfaces of intermediate and front glass elements 12 b′and 12a′ to provide a glass laminate assembly. That glass assembly issubstituted for front glass element 12 just as assembly 45 of FIG. 5. Aswith assembly 45, mirror assembly 55 has increased mechanical strengthdue to the laminate construction of the front glass panel, mayincorporate scatter preventing, anti-lacerative layers 14 or 36 on thefront surface of the front glass element 12 a′ for safety purposes, andreduces UV radiation transmitted into the assembly due to the UVabsorbing and blocking function of the sheet polarizer layer 57 and anylayer 14 or 36 to increase the lifetime of the assembly.

In FIG. 8, where like numerals indicate like parts to those describedabove, mirror assembly 60 includes a front glass element 62 formed fromone of several types of specialized glass rather than conventional sodalime window glass. For example, front glass element 62 may have a higheriron oxide content of within the range of about 0.2% to 0.9% by weightthereby increasing the ultraviolet radiation absorption, blockage and/orscreening effect. Similar improvement can be obtained using highercerium oxide content of 0.2% to 0.9% by weight concentration. Otherspecialized glasses which have high visible transmission but are strongabsorbers in the ultraviolet electromagnetic region can be usedincluding NOVIOL™ glasses as described in “Spectral-TransmissiveProperties and Use of Eye-Protecting Glasses” by R. Stair in NationalBureau of Standards Circular 471 (1948). A two millimeter thick sheet ofNOVIOL™ 0 CG306 (National Bureau of Standards Circular, 471 (1948))transmits only about 12% of the incident ultraviolet radiation at 360nanometers in contrast to transmission of approximately 70% of theincident ultraviolet radiation at 380 nanometers with a conventionalsoda lime window glass sheet. This is true even when such NOVIOL glassis coated with indium tin oxide as an electrical conductor. Conventionalsoda lime glass begins to screen out significant amounts of ultravioletradiation only below about 300 nm.

Other useful specialty glasses include UV-36™ glass available from HoyaCorporation of Tokyo, Japan having an average transition wavelength ofabout 360 nm such that it cuts off ultraviolet radiation below thatwavelength. Transition wavelength is the wavelength at the midpoint ofthe transition interval where glass goes from being highly transmittingto visible radiation to being highly absorbing for UV radiation. Otherglasses which can be used include L-1B™ also available from HoyaCorporation having an average transition wavelength of 420 nm. Otherexamples include CS0501, No. 0-51™ available from Corning Glass Works,Corning, N.Y. having a transmittance less than 0.5% at 334 nm and lowerat shorter wavelengths but being highly transmitting in the visibleelectromagnetic region and FG-62™ available from Ohara Optical GlassManufacturing Company, Ltd. of Tokyo, Japan, having a UV cutoff justslightly below 400 nm. Such ultraviolet radiation reducing glasses maybe used either with or without scatter preventing, anti-lacerative, UVreducing layers 14 or 36 or the UV reducing coatings mentioned above.When used, however, the scatter preventing, anti-lacerative layers havethe added advantage of significantly strengthening such glass which, inmany instances, are mechanically weaker than conventional window glass.In addition such speciality glasses may be used in the laminateassemblies substituted for front element 12 as described with FIGS. 5and 7.

As mentioned above, elements 12, 16 may also be cut or cast from clearplastic sheet material such as acrylic or polycarbonate and used inplace of front element 62 of FIG. 8. Additives such as benzotriazolesand benzophenones may be incorporated in the plastic to reduce UVradiation transmission. Other UV reducing layers or coatings asdescribed herein, including polymer layers 14, 36, may also be used incombination with the plastic elements.

As shown in FIG. 9, wide band, ultraviolet radiation, dielectric,dichroic or reflective filter materials may also be used in conjunctionwith the front glass or plastic elements 12 or 62. Suitable dichroicfilter or reflective materials include thin film coatings 67 whichsignificantly reduce ultraviolet transmission. Thin film layers 67 canbe applied to any glass or plastic surface ahead of the UV vulnerableelectro-optic mirror medium 20 but preferably on front or first surface11. A suitable thin film coating is the ultraviolet wide band dichroicfilter available from Optical Coatings Laboratory, Inc. of Santa Rosa,Calif. When applied to the rear surface of front element 12 or 62 asshown in FIG. 9 in solid lines, coatings 67 are interposed between theelement rear surface and ITO coating 13 a. When applied to the frontsurface 11, however, thin film coatings 67 are interposed between thefront surface and the scatter preventing, anti-lacerative layer 14 or 36as illustrated in phantom. Thin film coatings 67 have a transmission ofvisible light over 80% at 550 nm with a sharply lowered transmission ofabout 5% at 400 nm at which level the thin films become reflecting to UVradiation.

As a substitute for the thin coatings 67, ultraviolet radiation blockingpaints or lacquers can be applied to the element surfaces provided suchpaints or lacquers are transparent to visible light. A suitable materialfor layer 70 is a lacquer supplied as ZLI-2456 transparent UV protectinglacquer which is a solvent based acrylic with added UV stabilizersmanufactured by E. M. Industries of Hawthorne, N.Y. Such lacquersubstantially reduces UV radiation transmitted into the assembly and ispreferably applied to front surface 11 of element 12 to avoid dissolvingin medium 20.

For example, the above UV protecting lacquer ZLI-2456 was coated on aone mm thick sheet of ITO conductive glass to a thickness of about 30microns. The transmission spectrum of such coated glass is shown in FIG.3. It has a sharp transmission cutoff below about 400 nm and greatlyreduces UV radiation in the 290-400 nm region as compared to thatnormally transmitted by ITO coated glass (see FIG. 4).

Thin film coatings or UV reducing paint or lacquer layers 67, 70 may beused with conventional soda lime window glass as front glass element 12,or with specialized UV radiation reducing or higher iron oxidecontaining glass, or other UV reducing elements 62 such as the plasticelements mentioned above.

As shown in FIG. 10, a further embodiment 75 of the laminateelectro-optic rearview mirror assembly is illustrated including ascatter preventing, anti-lacerative layer 77 similar to thepolyvinylbutyral//polyester composite layer 36 described above inconnection with FIG. 2 but also including silicone moieties chemicallyincorporated in the anti-lacerative composite. Polymer layer 77including the silicone additive prevents condensation and/or beading upof condensed water on the coated front surface 11 or front mirrorelement 12, 62 in high humidity conditions thereby providing ananti-fogging, anti-misting result. A material found useful asanti-lacerative, anti-fogging layer 77 is silicone impregnatedpolyurethane supplied under the trade name CLARIFLEX™ by Saint-GobainVitrage of Paris, France. UV reducing additives such as those describedabove in connection with FIG. 2 may also be incorporated in theanti-lacerative, anti-fogging layer to increase the lifetime of theassembly. Alternately, front glass element 12, 62 may be fashioned fromconventional soda lime glass, UV reducing specialized glasses, orpolymer plastics. It is also possible to utilize thin film coatings orUV reducing paints or lacquers 67, 70 on at least one surface of frontelement 12, 62 when the anti-lacerative, anti-fogging layer isincorporated.

It is also possible to incorporate UV radiation reducing or absorbingstabilizers directly in the electro-optic medium 20 injected orotherwise inserted in space 18. Such absorbers may be dissolved directlyin the medium, e.g., an electrochemichromic liquid. The UV absorbers areselected to be compatible with the ingredients of the medium 20, suchthat they do not affect the electrical performance and function of themedium or oxidize or reduce in the assembly.

As an example, a laminate electrochemichromic mirror was fabricated asdescribed in the above example in connection with FIG. 2 except that noanti-lacerative layer was used over front glass element 12. In addition,UV stabilizers CYASORB™ UV1084 and CYASORB™ UV5411 were added to theelectrochemichromic active solution prior to filling into the gap 20between front glass 12 and a back glass 16. Concentration for the UV1084was 0.6% by volume and the UV5411 was 0.6% by volume g/cc.

As shown in FIG. 14, where like numerals indicate like parts to thosedescribed above, another embodiment 85 of the laminate, electro-opticrearview mirror assembly also includes a laminate glass assemblysubstituted for the front glass as is the case in embodiments 45 and 55in FIGS. 5 and 7 above. The front or first, laminate assembly 86includes a front or first glass panel 12 d having parallel front andrear surfaces adhered to an intermediate glass panel 12 e also havingparallel surfaces by an interlayer 12 c of polyvinylbutyral (PVB) oranother interlayer as described below. As in the prior embodiments,layer 12 c is adhered to the rear surface of glass panel 12 d and to thefront surface of glass panel 12 e by heat and pressure lamination suchas with the conventionally known autoclave method or the like. Inembodiment 85, however, glass panel 12 d is formed from a blue tintedspecialized glass which significantly reduces UV radiation transmissionwhile maintaining high visible light transmission. The rear surface 13of glass panel 12 e is coated with an indium tin oxide layer 13 a whichis, in turn, sealed with the front ITO coated surface 17 of rear glasselement 16 by seal 29 to provide electro-optic media receiving space 18as in the above embodiments.

Preferably, the blue tinted specialized glass 12 d is formed fromSOLEXTRA 7010™ blue tinted glass available from Pittsburgh Plate GlassIndustries, Pittsburgh, Pa. Graphs illustrating the percent transmissionof both ultraviolet and visible light for a 2.3 mm thick pane ofSOLEXTRA 7010™ glass are shown in FIGS. 22a and 22 b. SOLEXTRA 7010™glass is highly visibly transmitting at the 2.3 mm thickness, i.e., 83%transmission overall using a Standard Illuminant C and a photopicdetector (FIG. 22b). Also, this glass appears light blue in transmissionand strongly absorbs UV radiation below about 340 nm (FIG. 22a). At thisthickness, Solextra 7010™ passes only about 2% of the incident solarenergy in the 250-350 nm range. In the 350-400 nm region, it passesabout 67% of the incident solar energy.

Alternately, glass panel 12 d may be formed from SUNGLAS™ Blue, a bluetinted glass from Ford Glass Co., Detroit, Mich. The spectraltransmission for a 3 mm pane of SUNGLAS™ Blue, a blue tinted glass isshown in FIGS. 23a and 23 b. This glass is highly visibly transmittingat this thickness, i.e., 72% transmission overall with StandardIlluminant C and a photopic detector (FIG. 23b), appears light blue intransmission and strongly absorbs ultraviolet radiation below about 330nm (FIG. 23a). Such thickness of SUNGLAS™ Blue, a blue tinted glasspasses only about 11% of the incident solar energy in the 250-350 nmrange and 67% of the incident solar energy in the 350-400 nm range.

The above specialized glasses may also be used for second glass panel 12e or both panels 12 d and 12 e. Whether or not to use such specializedglass in both panels 12 d and 12 e is dictated by the degree of UVradiation protection desired, and by the degree of attenuation allowablein visible transmission of light that is concurrent with use of eventhicker panes or multiple panes of blue tinted or similar lightfiltering panels.

Mirror assembly 85 incorporating one or more blue glass panels providesa unique advantage. As described above, UV radiation stabilizers may beadded to enhance the UV radiation stability of an electrochemichromicsolution used in a rearview mirror assembly. Broad UV radiationstabilizers such as CYASORB 24™ from American Cyanamid Company of Wayne,N.J., UNINUL D-50™ from BASF Wyandotte Corporation, Parsippany, N.J., orTINUVIN 327™ from Ciba Geigy, Hawthorne, N.Y., impart a yellow color toelectrochromic or electrochemichromic solutions or materials, especiallywhen they are added in high concentrations where they are most effectivein protecting UV vulnerable materials. Yellow is aestheticallydispleasing in many applications and is particularly displeasing whenused in rearview mirrors. Also, when electrochemichromic solutions areexposed to prolonged dosages of high intensity UV radiation, such asoccur during natural weathering in sunny climates, those solutionsfrequently turn a yellowish hue which is aesthetically displeasing tothe consumer. It has been found that use of specialized blue glass, suchas that described above, allows use of higher concentrations of broad UVradiation stabilizers in electrochemichromic solutions than otherwisewould be consumer tolerable due to yellowing.

As an example of an electrochemichromic device constructed according toFIG. 14, an electrochemichromic solution was formed from 0.025Mmethylviologen perchlorate, 0.025M 5,10-dihydro-5,10-dimethylphenazine,0.025M tetraethylammonium perchlorate and 12.5% wt/vol CYASORB 24™ UVradiation stabilizer, all dissolved in 2-acetylbutyrolactone. Whenfilled in cavity 18 of embodiment 85 as shown in FIG. 14, cavity 18having a 150 micron thickness and using 15 ohms/sq indium tin oxide(ITO) transparent coatings 13 a, 17 a and with glass panels 12 d and 12e both fabricated of 1.6 mm standard, clear, soda lime glass laminatedtogether with a commercially available, clear PVB interlayer 12 cSAFLEX™ SR#11 from Monsanto Company of St. Louis, Mo., at zero potentialand with a silver mirror reflector such as reflective layer 26 behindthe assembly, the light reflected off mirror embodiment 85 has adistinct yellow tint and measures about 80% reflectivity using StandardIlluminant A and a photopic detector. Because consumers in automobilesare accustomed and appreciative of “silvery” reflection such as is foundon interior and exterior automotive mirrors of conventional design, themarked yellow tint makes use of high concentrations of broad UVradiation absorbers commercially disadvantageous. Yet, such highconcentrations of UV absorbers have the advantage of affording greaterUV protection and, therefore, prolong the commercial life ofelectrochemichromic rearview mirror devices, particularly when used onthe outside of a vehicle.

However, when a 2.3 mm pane of SOLEXTRA 7010™ was substituted as thefirst glass panel 12 d, with all other factors being the same for theexample of embodiment 85 as described above, the reflection as seen inthe mirror reflector was no longer yellow but had a color or tintdescribed as gun metal blue to neutral silvery. This is a much moreacceptable and commercially desirable reflective color than theyellowish tint previously obtained. Because SOLEXTRA 7010™ glass panel12 d naturally filters out yellow light thereby absorbing undesirableyellow tint, the integrated reflection at zero potential in this versionof the assembly is lower than that using clear glass, i.e., about 63%reflectivity using Standard Illuminant A and a photopic detector.However, such transmission is still sufficiently high to allowsuccessful use in vehicles, particularly as outside mirrors.

Yet another advantage is obtained using embodiment 85 and thespecialized glass panels 12 d or 12 e therein. Blue mirrors areparticularly well-suited to night driving. FIG. 24 illustrates therelative spectral power output versus wavelength of a CIE StandardIlluminant A and for CIE Standard Illuminant C. Illuminant A is aPlanckian radiator at 2856K and, thus, is similar to an automobileheadlamp. Illuminant C provides light similar to average daylight. Alsoincluded on FIG. 24 are the wavelengths of light which form the mainbands of color in the visible spectrum. By day, rearview mirrorillumination is natural daylight (similar to Illuminant C). By night,however, mirror illumination will be that of headlamp output (similar toIlluminant A) superimposed upon nighttime ambient light which isessentially spectrally unbiased. Vision from a mirror is also dependenton the spectral sensitivity of the driver's eye. The spectralsensitivity of the human eye depends on its light adaptation. If brightadapted, vision is photopic and the spectral sensitivity is as shown inFIG. 25. If dark adapted, however, vision is scotopic and sensitivityshifts toward the blue. Between these two extremes vision is mesopic.Almost all night driving is in the mesopic range of adaptation becausethe reflection of the driver's own headlights from the road providesufficient illumination to maintain the adaptation level above thescotopic range even on a very dark, unlit road. Because a headlamp emitsefficiently in the yellow/orange/red region of the visible spectrum, butrelatively poorly in the blue region as shown in FIGS. 24 and 25, andbecause a driver's eyes when driving at night are somewhat moresensitive to blue light, mirrors which optimize reflectance in the bluespectral region but minimize reflectance in the yellow/orange/red regionbest match human eye sensitivity in day and night conditions, are mostefficient at reducing headlamp glare and are desirable as both insideand outside rearview mirrors. Therefore, embodiment 85, which includesthe specialized tinted glass panel or panels, is efficient in absorbingor filtering out substantially more light in the yellow/orange/redregions of the visible spectrum than in other regions of the visiblespectrum. It tends to mask yellowness due to any inclusion of UVradiation absorbers, or due to any degradation of the EC or ECC materialitself, efficiently absorbs headlamp glare, provides a pleasing,attractive reflective color, and allows matching to visible blue tintedcolors on outside mirrors when one side of the vehicle has anelectro-optic mirror assembly for the driver and the other has aconventional, blue tinted, passenger-side mirror. In addition, the bluetinted embodiment 85 of the present mirror assembly is more restful on auser's eyes since any yellowness otherwise present in an electro-opticmirror assembly incorporating UV radiation stabilizers is a moreefficient reflector of light from a yellow headlight and, thus, wouldreflect more glare to a user's eyes than a comparable blue tintedmirror. Also, a commercially useful advantage of SOLEXTRA 7010™ andSUNGLAS™ Blue glass panels is that they are relatively inexpensive,namely, generally about two to three times the already low commoditycost of conventional, clear, soda lime glass.

Alternately, SunBlue™ glass from Asahi Glass Company, Tokyo, Japan, canbe used for one or both panels 12 d and 12 e. SUNBLUE™ is a blue tintedfloat glass incorporating added iron content and has a visible lighttransmission of 83% at a 3 mm thickness (per JIS-R-3106) and a UVradiation cutoff below about 330 nm.

Also, SUNGLAS™ Green from Ford Glass, Detroit, Mich., a green tintedglass, could be used for either or both of glass elements 12 d and 12 ein embodiment 85. As shown in FIG. 26b, such glass, in a 3 mm thickness,is highly light transmitting in the visible spectrum, i.e., 82%transmission overall with Standard Illuminant C and a photopic detector.It is also slightly green tinted and cuts off UV radiation transmissionbelow about 330 nm as shown in FIG. 26a. This glass in such thicknesstransmits only about 6% of the incident solar energy in the 250-350 nmregion, and about 60% in the 350-400 nm region.

A preferred material for the interlayer 12 c of embodiment 85 iscommercially available polyvinylbutyral (PVB) sheeting such as SAFLEX™SR#11 PVB mentioned above. Such commercially available PVB sheeting iscommonly used in automotive and architectural products and is formed bycombining PVB resin with added UV absorbers, as described earlier. Suchcommercially available polyvinylbutyral (PVB) sheeting is heavilyplasticized with at least about 19 parts of plasticizer per 100 parts ofpolyvinylbutryal resin using plasticizers such as triethyleneglycoldihexoate, triethyleneglycol di-2-ethyl butyrate, tetraethyleneglycoldi-n-heptanoate, di-n-hexyl adipate, butyl benzyl phthalate, and dibutylsebacate. FIGS. 27a and 27 b illustrate the ultraviolet and visiblespectral transmission of a sheet of SAFLEX™ SR#11 PVB adhered betweentwo 1.6 mm conventional, clear, soda lime glass panels. Such a laminatedassembly, using clear glass and SAFLEX™ SR#11, transmits only about 8%of the incident solar energy in the 250-350 nm region and about 54% ofsuch energy in the 350-400 nm region. When laminated, SAFLEX™ SR#11sheeting is water clear in light transmission.

In general, various forms of SAFLEX™ polyvinylbutyral sheetinginterlayers are acceptable for use in this invention as UV reducinginterlayers. These include SAFLEX SR™, SAFLEX TG™ and SAFLEX TL™sheeting in thickness ranges between about 0.015 and 0.060 inch. ThickerPVB interlayers provide better UV radiation shielding but may causevisible distortion. Yet, thicker sheeting is acceptable if due care istaken during lamination. Generally, such SAFLEX™ sheeting is preferablyshipped and stored in a refrigerated or cold condition to prevent thesheeting from sticking to itself while easing handling and use. Othercommercially available clear PVB sheeting can be used. For instance, anarchitectural composition such as BUTACITE™ 14 NC-10 clear PVB sheetingfrom E. I. duPont de Nemours and Company of Wilmington, Del. is asuitable choice. BUTACITE™ is plasticized polyvinylbutyral which isplasticized with tetraethyleneglycol di-n-heptanoate, with a plasticizercontent (parts/100 parts resin) of about 38.5 or thereabouts. Whenlaminated between two panels of 2.3 mm conventional, clear, soda limeglass as shown in FIGS. 35a and 35 b. BUTACITE™ 14 NC-10 clear PVBsheeting transmits less than 0.1% of the incident solar energy in the250-350nm region and only about 25% in the 350-400 nm region.Alternatively, BUTACITE™ 140 NC-10, an automotive composition orBUTACITE™ 14 UV clear, an architectural composition PVB sheeting can beused.

Alternately, a blue or blue/green tinted interlayer 12 c′ may besubstituted to form embodiment 85′ of the mirror assembly as shown inFIG. 14. Preferably, BUTACITE™ Cobalt Blue 0547800 polymeric interlayersheeting available from E. I. duPont de Nemours and Company ofWilmington, Del. can be used. The ultraviolet and visible spectraltransmission of BUTACITE™ Cobalt Blue sheeting, when laminated betweentwo 2.3 mm standard, clear, soda lime glass panels is shown in FIGS. 28aand 28 b. Such sheeting is a highly light transmitting polymericmaterial having 78% overall visible light transmission with Illuminant Cand a photopic detector (FIG. 28b). It is blue in tint and highlyabsorbing in the UV radiation range below about 375 nm (FIG. 28a). Ittransmits only 0.01% of the incident solar energy in the 250-350 nmregion and about 24% of such energy between 350 and 400 nm. By reason ofits blue tint, BUTACITE™ Cobalt Blue sheeting also provides theadvantage of masking yellowness in the mirror to provide a commerciallyacceptable silvery or silver-blue reflection from assembly 85′, whilereducing headlamp glare and also matching existing blue exteriorrearview mirrors commonly used in many vehicles.

BUTACITE™ Cobalt Blue sheeting could be used alone or in combinationwith one or both panels 12 d, 12 e of embodiment 85 being specializedblue or green tinted glass. Other suitable blue tinted polymericsheeting interlayers include BUTACITE™ Automotive Blue Green 0377800,BUTACITE™ Automotive Green Blue 1107800 and BUTACITE™ Light Blue Green0377300 also available from E. I. duPont in Wilmington, Del. Inaddition, SAFLEX™ Blue Green 377300 available from Monsanto Company ofSt. Louis, Mo. may be used. The ultraviolet and visible spectraltransmission of SAFLEX™ Blue Green 377300 sheeting is shown in FIGS. 29aand 29 b. Alternately, SAFLEX™ Cool Blue 637600 or SAFLEX™ Solar Blue755800 polymeric sheeting could also be used.

With reference to FIG. 15, another embodiment 95 of the electro-opticrearview mirror assembly of the present invention, where like numeralsindicate like parts to those described above, incorporates a singleglass panel 97 having parallel front and rear surfaces but formed fromone of the blue or green tinted specialized glasses described above inconnection with embodiments 85 and 85′. Thus, for example, front glasselement 97, which also includes a coating of indium tin oxide 13 a onits rear or inner surface 13, may be formed from SOLEXTRA 7010™ bluetinted glass, SUNGLAS™ Blue glass, SUNBLUE™ glass or SUNGLAS™ Greenglass. When the blue tinted glasses are used, the resultant yellowabsorbing light advantages described above in connection withembodiments 85 and 85′ result in embodiment 95 as well. These glassesare highly efficient in absorbing or filtering out substantially morelight in the yellow/orange/red regions of the visible spectrum than inother regions of the visible spectrum. With reference to the visiblespectrum in FIG. 24, such specialized glasses preferentially absorbvisible light with wavelengths generally higher than about 560 nm. Inother respects, the embodiment 95 remains substantially the same asembodiment 60 of the mirror assembly. Optionally, panel 97 could be apanel of specialized blue or green tinted safety glass that has beentempered and/or toughened by conventional means which include thermaltempering, contact tempering and chemical tempering.

An alternate form 100 of the UV radiation reducing embodiment 65 shownin FIG. 9 is illustrated in FIG. 16. Mirror assembly 100, where likenumerals indicate like parts to those described above, includes a UVabsorbing paint or lacquer which is transparent to light in the visiblespectrum and may be applied as coatings 102, 104 on one or both of theinwardly facing surfaces of glass elements 12 a, 12 b or 12 d, 12 e.These are the surfaces of the glass panels which face one another andadhering interlayer 12 c. A preferred UV absorbing lacquer is PC-60 fromAmerican Liquid Crystal Chemical Corporation of Kent, Ohio which is asolvent based urethane with added UV stabilizers. The ultravioletspectral transmission of an approximately 32 microns thick coating ofPC-60 lacquer when applied to one surface of a 1.6 mm thick single panelof conventional, clear, soda lime glass is illustrated in FIG. 30. Whenapplied as a coating, PC-60 is highly visibly transmitting, i.e., about89% overall transmission with Illuminant C and a photopic detector, hasa slight yellow tint, and absorbs sharply in the UV radiation regionbelow about 390 nm. Between 250 and 350 nm, such a coating of PC-60lacquer transmits essentially none of the solar energy incident in thatregion. For incident solar energy between 350 nm and 400 nm, PC-60lacquer transmits only about 5%. Overall, such a coating of PC-60lacquer transmits only about 3% of the incoming solar energy in the250-400 nm region.

An alternate UV absorbing lacquer is ZLI-2456 mentioned above in layer70 and useful to form embodiment 100′ (FIG. 16). A 12 microns thickcoating of ZLI-2456 transmits only about 2% of the incident solar energyin the 250-350 nm region, and only about 9% of the solar energy normallyincident between 350 and 400 nm. ZLI-2456 is slightly more yellowish incolor and transmission than is PC-60 lacquer. Of course, UV absorbingpaint/lacquer coatings such as those described above may be used with UVabsorbing/filtering interlayers 12 c or 12 c′ as described above, orwhen either of glass panels 12 a, 12 d or 12 b, 12 e are formed fromblue or green tinted specialized glass as described above. Indeed, in apreferred form of embodiment 100, glass panel 12 d will be formed fromSOLEXTRA 7010™ or SUNGLAS™ Blue glass while the electro-optic media inspace 18 will include UV absorbing additives as described above. Theultraviolet spectral transmission of ZLI-2456 is shown in FIG. 31.

As a specific example of mirror assembly 100 shown in FIG. 16, anelectrochemichromic solution was formulated consisting of 0.02Mmethylviologen hexafluorophosphate and 0.02M5,10-dihydro-5,10-dimethylphenazine dissolved in 2-acetylbutyrolactone.To this was added 12.5% wt/vol CYASORB 24™ UV radiation absorber. Thiswas filled into a 150 micron thick cavity between panels 16, 12 b of ITOtransparent coated, 1.6 mm thick, conventional, clear, soda lime glass.The ITO coating on each glass panel was 15 ohms/sq and had a visibletransmission of 85%. A coating of UV absorbing ZLI-2456 lacquer wasspray coated on the front facing surface 103 of rear glass panel 12 band on the rear facing surface 101 of front glass panel 12 a each to athickness of about 11 microns. Glass panels 12 a, 12 b were thenlaminated by an interlayer 12 c of SAFLEX™ SR#11 PVB sheeting. Whentested under mercury UV radiation lamps at a temperature of about 80° C.for a period of approximately two weeks, such a mirror assembly wasfound to be exceptionally UV radiation stable. Integrated irradiation inthe 295-400 nm region within the UV radiation chamber used to acceleratenatural weathering was around 100 W/m². Initially electrochemichromicmirror devices with such UV and anti-scatter protection had a reflectionof approximately 81% at zero potential which dimmed to a reflectivity ofapproximately 8% when one volt potential was applied across ITO coatings13 a, 17 a which enclose the electrochemichromic solution. After over336 hours in the UV radiation chamber, the zero potential reflectivityremained high at around 80% and the mirror continued to dim to about 8%reflectivity when one volt was applied. The appearance of the mirrorremained essentially unchanged after such prolonged exposure to highintensity ultraviolet radiation. Also, when the safety performance ofthe mirror assembly was tested by impacting it with a 0.9 kg steel balldropped from a height of 1 meter, the SAFLEX™ SR#11 laminatinginterlayer securely retained all shards of glass such that they did notfly away and such that they remained securely held to the laminateinterlayer. Also, the SAFLEX™ SR#11 laminate interlayer did not fracturenor tear and was effective in ensuring that contact with chemicals usedwithin the electrochemichromic mirror assembly is minimized should themirror glass break in an accident. Because of the high concentration(12.5% wt/vol) of broad UV absorber CYASORB 24™ used in this embodiment,and because of the slight yellow tint inherent to ZLI-2456 UV absorbinglacquer, the reflection from this example of mirror assembly 100 had asomewhat yellow tint which is cosmetically undesirable in someapplications. However, when the front glass panel 12 a was replaced witha blue tinted glass panel 12 d as described in embodiment 85, thebenefits described above were achieved. Specifically, when a 2.3 mmpanel of SOLEXTRA 7010™ glass was used as front glass panel 12 d,reflectance at zero potential remained close to its initial 64% in spiteof over 336 hours of UV accelerated weathering testing as mentionedabove. Because of the use of blue tinted glass, the reflector lookedmore silvery-blue and was more consumer acceptable. Also, when dimmed byapplying one volt to the transparent coatings 13 a, 17 a, the mirrorcontinued to dim to its low reflection state of about 7% reflectivity,even after prolonged exposure to the intense UV radiation.

Also with reference to FIG. 16, an alternate embodiment 110 substitutesdifferent layers for paint/lacquer layers 102, 104 preferably in theform of a polymeric film such as clear SCOTCHTINT™ SH2CLX available from3M Corporation, St. Paul, Minn. Such SCOTCHTINT™ film may be adhered aslayers 112, 114 to one or both of the inner facing surfaces of glasspanels 12 a, 12 b or specialized glass panels 12 d, 12 e as describedabove, said placement on inner surfaces having the added advantage ofprotecting the potentially scratchable polymeric film behind glasspanels 12 a, 12 d. Film layers 112, 114 (FIG. 16) provide assembly 110with similar UV reducing advantages while maintaining strength andscatter preventing advantages due to the laminate front assembly as inembodiments 100 and 100′. The ultraviolet spectral transmission of asingle layer film of SCOTCHTINT™ SH2CLX adhered to a sheet of 1.6 mmconventional, clear, soda lime glass is shown in FIG. 32. SCOTCHTINT™SH2CLX is a highly visibly transmitting film, i.e., about 82% overalltransmission using Illuminant C and a photopic detector. It is alsoclear and absorbs sharply and intensely in the UV region below about 380nm. Preferably, SCOTCHTINT™ SH2CLX film is used in a form including apressure sensitive adhesive applied to one surface such that it may beeasily adhered to the rear facing surface of glass panel 12 a or 12 dand the front facing surface of glass panel 12 b or 12 e. Likewise, suchpolymeric film adds to the anti-scatter effect of the mirror assembly110 by retaining shards or splinters from glass panel 12 a, 12 d shouldit be broken upon impact. Also, by serving as a barrier film, they areeffective in ensuring that contact with the chemicals used within theelectro-optical mirror is minimized should the mirror glass break in anaccident. Alternately, polymeric film such as SCOTCHTINT™ SH2CLX may beused in combination with clear or tinted UV reducing interlayers 12 c or12 c′ such as SAFLEX™ as described above.

As an alternative to using polymeric sheeting 112, 114 in mirrorassembly embodiments 100, 100′ or 110 as described above in FIG. 16, aUV curable, pourable adhesive can be used to retain the glass panels 12a, 12 b or 12 d, 12 e together while simultaneously reducing UVtransmission as embodiment 120 (FIG. 16). A suitable ultraviolet curingpolyurethane adhesive modified so as to be UV curable is NORLAND NOA 65™available from Norland Products, Inc., New Brunswick, N.J., which iswater clear, highly transparent to visible light, includes a moderatemodulus of elasticity when cured such that it is not overly brittle anddoes not fracture upon impact, and includes an index of refraction of1.52 matched perfectly to that of soda lime glass (which has arefractive index of 1.52). NORLAND NOA 65 also adheres well to glass, isof relatively low viscosity (1,200 centipoise) such that it easily poursand spreads between two glass panels to allow lamination once cured. Italso has a relatively low modulus of elasticity (20,000 psi). Itsability to be cured with UV radiation is well-suited to manufacturingprocessing. FIG. 33 illustrates the ultraviolet spectral transmission ofa 35 microns thick coating of cured NORLAND NOA 65™ on a 1.6 mmconventional, clear, soda lime glass panel. Ultraviolet radiationtransmission is cut off below about 310 nm while only about 19% of theincident solar energy in the 250-350 nm region is transmitted whileabout 62% of the incident solar energy in the 350-400 nm region istransmitted.

Alternately, Norland NOA68, also a polyurethane adhesive modified so asto be UV curable and also available from Norland Products, Inc., can beused instead of NORLAND NOA 65. NORLAND NOA 68™ has a refractive indexof 1.54 matched closely with clear soda lime glass. It has a modulus of20,000 psi when cured and has an excellent adhesion to glass. NORLANDNOA 61™, which is a polyurethane adhesive modified so as to be UVcurable, can also be used although, with a modulus when cured of 150,000psi, it is somewhat more brittle. Alternately, DYMAX LIGHT-WELD 478™acrylic adhesive available from Dymax Corporation, Torrington, Conn. canbe used. This is a UV curing acrylic of Shore D hardness 65 that has arefractive index of 1.507 which is very close to that of soda lime glasswhen cured. Alternately, conventionally known UV curing optical epoxies,preferably of low modulus or with their modulus reduced through additionof reactive diluents and reactive flexibilizers, as is commonly known,can be used.

Should it be desired to further reduce the modulus of elasticity of thecured adhesive, clear plasticizers or clear low molecular weight epoxiescan be added to the UV curing adhesives so that they are less brittleafter curing, and such that they have even better lamination safetyperformance. For example, cyclohexanedimethanol diglycidyl ether such asHELOXY MK107™ from Wilmington Chemical Corporation of Wilmington, Del.can also be added to NORLAND NOA 61™, NOA 65™ or NOA 68™ in quantitiesup to 30% wt/wt or more (i.e., % grams of MK107™ added to grams ofNOA61, etc.) to plasticize them. HELOXY MK107™ has a refractive indexclose to 1.48 which is also well-matched to that of clear soda limeglass. At high concentration of added MK107, the UV cured NOA61, NOA65or NOA68 materials are quite flexible and somewhat elastic such thatthey are well-suited for use as anti-lacerative layers and as laminateinterlayers.

As an alternative to the UV curing adhesives described above, thermallyor catalytically cured adhesives can also be used to retain glass panels12 a, 12 b and 12 d, 12 e together while simultaneously acting as a UVradiation reducing agent. As with the UV curing adhesives, the thermallyor catalytically cured adhesives are preferably water clear, highlytransparent to visible light, closely matched to the index of refractionof glass, while being of moderate modulus of elasticity when cured so asnot to be overly brittle nor to fracture upon impact and thus impairretention of any glass fragments or shards. A suitable system includes amodified epoxy adhesive formed from 15% wt/wt EPON 828™ epoxy resin,mentioned above in embodiment 10, 35% wt/wt HELOXY MK107™, and 50% wt/wtCAPCURE 3-800™ mercaptan curing agent available from Diamond ShamrockChemicals Company, Morristown, N.J. These ingredients are mixed togetherin a container and subsequently spun in a centrifuge at approximately4,500 rpm for about ten minutes to remove entrained air. The resultantviscous mixture is clear and is applied between panels 12 a, 12 b or 12d, 12 e. The resultant assembly so formed is fired at about 110° C. forabout one hour followed by firing at 140° C. for a further hour. Suchfiring causes the adhesive mixture to cure to an adhering but moderatemodulus of elasticity, somewhat flexible, optically clear laminate. Theultraviolet transmission of a 500 microns thick cured coating of thisadhesive mixture, coated onto a 0.063 inch conventional, clear, sodalime glass panel is shown in FIG. 34. Such material transmits about 35%of the incident ultraviolet solar energy in the 250-350 nm regionthereby providing good inherent UV absorbing properties.

Also, it is possible to enhance the already good inherent UV radiationabsorbing properties of these UV, thermally, or catalytically curedadhesives by adding any of the UV absorbing materials such as UVINULD-50™, UVINUL D-49™, UVINUL 400™, TINUVIN P™, TINUVIN 327™, TINUVIN328™, or CYASORB 24™ to the liquid adhesives prior to their cure.

The UV, thermally, or catalytically cured adhesives can also beoptionally dyed so that they have a slight bluish tint and provide anddesirable properties of the electro-optic mirror assemblies includingspecialized blue tinted glass panels or blue tinted interlayers. Forexample, taking the specific adhesive mixture of EPON 828™/HELOXYMK107™/CAPCURE 3-800™ described above, such mixture can be dyed blueusing NEOZAPON BLUE™ 807, a phthalocyanine dye available from BASFWyandotte Corporation, Parsippany, N.J., added in about 0.5% to 1% byweight. When laminated between two 0.063 inch thick panels of clear,conventional, soda lime glass, such a dyed mixture, at 0.5% dyeconcentration, was highly visibly transmitting (78% transmission usingIlluminant C and a photopic detector), was tinted blue, and was highlyabsorbing in the UV region with only 30% transmission of incident solarUV energy in the 250-350 nm region.

In any of the above mirror assembly embodiments, and especially thoseutilizing one or more panels of clear soda lime glass not already tintedblue or green as in embodiments 85, 85′, 100′, 110 or 120, a blue,electrochemically inert dye may be added to the electrochromic orelectrochemichromic solution itself to provide the advantages ofabsorbing more light in the yellow/orange/red region of the visiblespectrum than in other regions of the visible spectrum. Such a dyedassembly will provide similar advantages to those including specializedblue tinted glass or blue tinted interlayers. For example, a suitablematerial such as NEOPEN 808™, a blue dye of the phthalocyanine type, isavailable from BASF Wyandotte, Parsippany, N.J. Such material, dissolvedto a concentration of 0.1% wt/vol in p propylene carbonate (a commonsolvent used in electrochemichromic solutions), and when placed in a 1mm pathlength cell, transmits about 60% of the visible spectrum(Standard Illuminant C and a photopic detector), and transmits onlyabout 9% of the incoming solar UV energy in the 250-350 nm region.

ELECTROCHROMIC VEHICULAR GLAZING

Referring now to the window or glazing assembly embodiment of thepresent invention, FIG. 37 illustrates a laminate, electrochromicwindow/glazing assembly 200 having a first optically transparent element212 which is scatter and anti-lacerative protected with a resinous,polymeric or other coated or applies layer 214 on its inner surface 211.Layer 214 is preferably formed from tear-resistant, resilient materialsuch as plasticized polyvinylbutyral (PVB) sheeting having a preferredthickness of from about 0.005 inches to about 0.060 inches. Element 212is preferably formed from a sheet of conventional soda lime window glasshaving a preferred thickness of from about 0.02 to about 0.25 inches asis second element 216, which is spaced slightly outwardly from firstelement 212 to define a gap or space 218 for receiving an electrochromicmedium 220. Also, element 216 is generally located closest to theoutside of the vehicle and, as such, is located closest to the solarsource of UV radiation. Generally, elements 212 and 216 are of compound,matched curvature. As explained hereinafter, elements 212, 216 may alsobe optically clear resinous, polymeric sheets to further preventfragment scattering and lacerative injuries if broken, to further reduceUV transmission, and to reduce weight. Layer 214 also providesultraviolet protection for the interior cabin of the vehicle andprotects against contact with whatever chemicals are used inelectrochromic medium 220 if element 212 should crack or break.

Space 218 is formed between the generally parallel or tangentiallyparallel outer surface 213 of first glass element 212 and inner facingsurface 217 of second glass element 216. Preferably, each of the innerand outer surfaces 213, 217 is coated with a layer of indium tin oxide(ITO) which is substantially transparent to incident visible light yetis sufficiently electrically conductive to enable application of anelectric field or voltage across space 218 between ITO layers 213 a, 217a. Layers 213 a and 217 a also can be other transparent conductors suchas doped tin oxide, doped zinc oxide, and the like. Electrical energy isprovided by wire leads 22, 24 secured in conventional manner to theperipheral portions of ITO coatings 213 a, 217 a as shown in FIG. 37.

In order to confine and retain the electrochromic medium in gap 218, aperipheral seal 229, formed from an epoxy material which adheres well tothe ITO coatings 213 a, 217 a on glass surfaces 213, 217 is appliedadjacent the periphery of glass elements 212, 216. A suitable epoxysealing material is EPON 828™ epoxy sealant from Shell Chemical Companyof Houston, Tex. cured by polyamide based curing agents such as V-40™curing agent from Miller Stephenson Company of Danbury, Conn. The epoxyis preferably silk screened onto the inner surface of the first glasselement 212 or the second glass element 216 or onto both glass elements.The corresponding glass element is then placed face to face with thestill tacky epoxy. Seal 229 is then fully cured, typically by placingthe assembly into an oven at 110° C. for three hours. Gap 218 can thenbe filled by a variety of means such as simple injection ofelectrochromically active material using a syringe. The variouselectrochromic media proposed for use with the electro-optic mirror arealso suitable for use as the electrochromic medium 220. In addition, theelectrochromic medium 220 can be one of the types described in the SAEPaper #900419, the reference to which is incorporated herein.

FIG. 37 depicts an embodiment of the present invention where element 216is a laminated composite formed from a pair of glass panels 251, 252like element 212. A specialized near-infrared reflector 250 can bedirectly deposited onto the inwardly facing surface 255 of panel 252. Inthis arrangement, element 252 protects reflector 250 from the outsideenvironment and from abrasive damage as in car washes and the like.Reflector 250 (shown enlarged in FIG. 38) preferably incorporates atleast one semi-transparent elemental metal thin film 256 of physicalthickness in the range of between about 80 angstroms to 300 angstromsand of sheet electrical resistance of no greater than about 8ohms/square. Elemental thin metal film 256 is preferentially sandwichedbetween optically transparent thin metal compound films 258 a, 258 b.Thin metal compound films 258 a, 258 b may be metal oxide, nitride,halide or sulfide thin films. Among the possible thin metal compoundfilms are the following: zinc oxide, titanium oxide, vanadium oxide,zirconium oxide, tungsten oxide, indium oxide, bismuth oxide, magnesiumfluoride, cerium oxide, indium/tin oxide, tin oxide, zinc sulfide,silicon oxide and silicon nitride. As shown in FIG. 39, in analternative embodiment, near infrared reflector 250 can be depositedonto a polymer sheet or film 253, which polymer sheet or film itself iscapable of providing UV protection and shatter protection.

Layer 254 in FIG. 37 is an adhesive substance for bonding panels 251 and252 together. Layer 254 may preferably be a specialized tear-resistant,resilient interlayer of thickness 5 mils or greater such as BUTACITE™ 14NC-10 plasticized PVB sheeting from E. I. duPont de Nemours and Companyof Wilmington, Del. which imparts UV protection to electrochromic medium220 and imparts scatter protection directly to element 216, andindirectly to element 212. Layer 254 can act to contain theelectrochromicallly active material contained in gap 218 should outerpanel 252 and panel 251 shatter under impact. Also, should tinting bedesired, then tinted plasticized polyvinlybutyral sheeting such asSAFLEX OPTICOLOR SYSTEM™ interlayers from Monsanto Company of St. Louis,Mo. can be used. Preferably, such tinting causes the assembly to appearblue or green in transmission. This preserves the natural color of thesky, spectrally filters yellow light and, thus, protects from solarglare, thereby enabling use of high concentrations of UV stabilizers andreducing UV transmission through the assembly as a whole and into theelectrochromic medium in particular while simultaneously andsynergisticallly providing safety protection against contact with brokenglass and the chemicals used in the electrochromic medium.

A second embodiment 202 of the window glazing assembly invention isshown in FIG. 40 where element 212 is the laminated composite formedform glass panels 251, 252. The specialized near-infrared reflectorlayer 250 is sandwiched between elements 251 and 252 on the inwardlyfacing surface of element 251. Thus, relative to the vehicle outside,layer 250 is below the electrochromic medium 220. Such a construction isless desirable than that shown in FIG. 37 because layer 250 is not in aposition to protect electrochromic medium 220 from the damaging effectsof solar near-infrared and ultraviolet radiation.

FIG. 36 shows the solar energy spectrum Air Mass 2 that constitutes thesolar load incident on an automobile. The solar energy for Air Mass 2 isthe insolation through two standard atmospheres using data originallyproposed by P. Moon Journal Franklin Inst., 230, 583 (1940). Most of thesolar intensity for Air Mass 2 is between 300 and 2100 nm. On theaverage, ultraviolet (UV) constitutes 3% of solar radiation (up to 400nm), while visible light or radiation is 48% (between 400 and 700 nm)and near-infrared (NIR) is 49% (between 700 and 2100). If a perfectfilter could be designed to reject all solar NIR radiation, nearly halfof the solar energy could be rejected without any loss of visibility.

As a specific illustration of the benefit achievable through use of aspecialized near infrared reflector in combination with anelectrochromic medium, UV, luminous an solar transmission studies wereperformed on both an electrochromic cell alone and on the combination ofcommercially available heat mirror constructions with the sameelectrochromic cell. The cell was formed by sandwiching anelectrochemichromic solution comprising;

0.035 M ethylviologen perchlorate 0.035 M5,10-dihydro-d,10-dimethylphenazine 5% wt/vol UMINUL ™ 400(2,4-dihydroxy-benzophenone)

dissolved in a solvent comprising 75% 3-hydroxypropionitrile and 25%glutaronitrile. The cell gap was 135 microns. The ITO transparentconductors sandwiching the electrochemichromic medium were of half-wave(about 1500 angstroms) thickness and of sheet resistance 15 ohms/squareor thereabouts coated onto 0.043″ thick soda lime glass elements.Measurements were taken over four spectral ranges, namely, ultraviolet(UV), visible, near-infrared (NIR), and solar (Air Mass 2), of theattenuating characteristics of this electrochromic cell construction,both when the cell was bleached and when it was colored under 1 voltapplied potential. The results are summarized in Table A.

TABLE A Conventional Electrochemichromic Window Half-Wave ITO ElectrodesUV VISIBLE NEAR-IR SOLAR 300-400 nm 400-800 nm 800-2500 nm 300-2500 nm %T/% R % T/% R % T/% R % T/% R Bleached   9%/5.5% 77%/10% 47%/17% 63%/13%Colored 0.01%/5.3% 14%/6%  37%/16% 23%/10% (1.0 volt) % T = PercentTransmission % R = Percent Reflected

As can be seen from the data, this electrochemichromic window transmitsabout 63% of incident solar radiation when bleached and about 23% ofincident solar radiation when fully colored under 1.0 volt appliedpotential.

Table B summarizes the results of similar measurements obtained when theelectrochemichromic window cell of Table A was combined with a heatmirror glass commercially available from Cardinal Glass Inc. of SpringGreen, Wis. in a manner similar to that shown in FIGS. 37 and 38, butwithout any anti-lacerative layer 214.

TABLE B Electrochemichromic Window Combined with Cardinal Heat MirrorHalf-Wave ITO Electrodes UV VISIBLE NEAR-IR SOLAR 300-400 nm 400-800 nm800-2500 nm 300-2500 nm % T/% R % T/% R % T/% R % T/% R Bleached  7%/13% 64%/14% 24%/46% 46%/27% Colored 0.1%/13% 12%/11% 18%/46%14%/25% (1.0 volt)

The Cardinal Heat Mirror (see FIG. 38) comprises a thin silver film 256of thickness less than 300 angstroms incorporated in a multilayer thinfilm stack which includes a sandwich of zinc oxide thin film layers 258a, 258 b on glass panel 252. Note, from Table B, that combination of theCardinal Heat Mirror with the electrochmichromic window allowspreservation of a relatively high luminous visible transmission of 64%(of benefit for automotive glazing such as front side, or rear windowswhere preservation of high transmittance in the bleached state may be ofsafety importance) while simultaneously significantly further reducingthe total solar load transmitted into the automobile interior.

In the bleached state, use of the Cardinal Heat Mirror achieves areduction in solar transmittance from 63% to 46% and, in the coloredstate, from 23% down to 14%. Similar benefits can be obtained bycombining alternate thin film stacks to that utilized in the CardinalHeat Mirror with the electrochemichromic window. However, it isimportant that the elemental metal layer 256 used therein has a highcarrier density and high charge mobility so that its plasma edge risesearly in the near-IR region thereby reflecting the maximum near-IR solarradiation. Sheet electrical resistance is preferably below about 8ohms/square or thereabouts. Optionally, and given that metal layer 256is not contacting the electrochromic medium and, as such, iselectrically isolated therefrom, electric current can be passed acrossmetal layer 256 via wires or other electrical connections secured tolayer 256 from the automobile electrical system for the purpose ofheating and defrosting the glazing assembly when so desired duringwinter months and the like. The thin elemental metal layer 256preferably has a physical thickness between about 80 angstroms and 300angstroms. Below 80 angstroms, the deposited coating is insufficientlycontinuous to yield good electrical conductivity and to achieve goodnear-IR reflectivity. Above 300 angstroms, the deposited thin elementalmetal is overly opaque and overly luminous reflecting to be desirablefor high transmittance applications, even when antireflected in amultilayer optical stack. These effects are illustrated in FIGS. 36A and36B.

FIG. 36A shows the % luminous transmission (with the source beingStandard Illuminant A) as the thickness of a silver elemental metalfilm, deposited onto a soda lime glass substrate, increases in thicknessfrom about 60 angstroms to about 400 angstroms. Note that % luminoustransmission falls off rapidly and dramatically with increasingthickness of the silver film. However, when a construction such as isshown in FIGS. 38 or 39 is used with layer 258 a being 180 angstromsthick film of titanium dioxide (refractive index 2.5), and layer 258 balso being a 180 angstroms thick film of titanium dioxide (refractiveindex 2.5), and with these layers sandwiching a layer of 256 ofelemental silver, then, and as shown in FIG. 36B, the thickness of thesilver layer can be increased to 300 angstroms, or thereabouts, whilesustaining % luminous transmission above 50%.

For many automotive glazing constructions, and especially for thoseinvolving compound curvature, it is desirable that the specializednear-infrared reflector be deposited onto a flexible element like layer253 in FIG. 39 such as MYLAR™ polyester film available from E. I. duPontof Wilmington, Del. Such polyester film is typically supplied in filmthicknesses ranging from 0.001 to 0.050 inches or thereabouts. There areseveral advantages to use of a flexible polymer element for heat mirrorcoating. Being flexible and polymeric, it can be readily conformed undermodest temperature and pressure, thus facilitating constructions wherethe rigid elements 212, 216, 251, 252, and the like are of compoundcurvature such as commonly found for automotive glazing. Also, theflexible polymer film can form a barrier affording protection againstchemical leakage should be typically glass elements it contacts break orcrack.

Such heat mirror coated flexible polymer film like 253 can beeconomically supplied coated on both surfaces with a conventionalpressure-sensitive adhesive so that when sandwiched between glass as inthe constructions contemplated in this invention, the flexible polymerfilm itself can afford a degree of safety protection to occupants in anaccident. In addition, the polymer film itself can be a host for UVabsorbers and so can supplement other UV attenuating means present inthe construction as mentioned above regarding rearview mirrors (such asUV absorbers in solution in the electrochromic medium, such as glassesof increased iron oxide and/or cerium oxide content, use of aspecialized UV absorbing glass for elements 212, 216, 251, 252, etc.).Further, the polymer film may be tinted to facilitate construction oftinted electrochromic windows.

An example of a near-infrared reflector forming a heat mirror which isdeposited upon a flexible polymer film and is suitable to combine withan electrochromic window to achieve the objectives of this invention isHM-55 film from Southwall Corporation of Palo Alto, Calif. HM-55includes a thin film coating of silver sandwiched between indium oxidethin film layers, all in turn deposited onto a thin MYLAR™ flexiblepolymer film. Table C summarizes the results obtained when theelectrochemichromic window cell of Table A was combined with a HM-55heat mirror film by application to the outer glass surface.

TABLE C Electrochemichromic Window Combined with HM-55 Heat MirrorHalf-Wave ITO Electrodes UV VISIBLE NEAR-IR SOLAR 300-400 nm 400-800 nm800-2500 nm 300-2500 nm % T/% R % T/% R % T/% R % T/% R Bleached3.8%/43% 37%/46% 23%/77% 25%/58% Colored   0%/43%  6%/44% 18%/77% 6%/58% (1.0 volt)

As indicated, the HM-55 film is relatively attenuating in the visibleregion so that this combination is best suited for applications such asan automotive sunroof where high bleached state transmittance is notnecessary but where it is highly desirable to be darkly attenuating inthe colored state and where exceptional solar performance in both thebleached and the colored states is desired. As Table C indicates, solartransmittance in the bleached state is only 25% and this decreases to amere 6% when the electrochemichromic window is dimmed under 1.0 voltapplied potential. Thus, the use of a thin elemental metal layer incombination with an electrochromic window (which itself is relativelysolar transmitting in both the bleached and colored state) achievesexceptional solar performance for the combination. Note also that the UVtransmission in the bleached state using HM-55 film is substantiallyreduced over that achieved with previously described designs, such UVreduction being beneficial in avoiding degradation of interior trim suchas seats, carpets, etc. Note also the low near-infrared solartransmittance through this assembly. Such low UV and near-IRtransmittance, even in the bleached state, can have an important safetyimplication. The human eye is not sensitive to radiation in the UV andnear-IR spectral region. Thus, it is important that UV and near-IRtransmission be minimized to avoid eye damage, and particularly retinaldamage, for consumers viewing the sky and the sun through theelectrochromic window assembly.

As an alternative to HM-55, HM-77, HM-66, HM-44, and HM-33 heat mirrorcoatings on polyester film, all available commercially from SouthwallCorporation of Palo Alto, Calif., can be used. HM-77 and HM-66 are lowreluctance heat mirrors most suited to automotive glazing applicationslike front, side, and rear windows where high luminous transparency isof benefit. HM-44 and HM-33 are low transmittance heat mirrors mostsuited to automotive glazing applications such as sunroofs where hightransparency is not a requirement. Also, all such heat mirror multilayerstacks could be deposited onto tinted polyester film to facilitateproduction of tinted electrochromic window assemblies. Alternatively,the heat mirror polyester films could be combined with tinted glass suchas GRAYLITE™, a dark gray tinted glass available from PPG IndustriesInc., Pittsburg, Pa.

Alternatively, the specialized near-infrared reflectors described abovecould be combined with specialized UV-absorbing glasses such asAZURLITE™, a light aqua (blue-green) tinted glass available fromPittsburg Plate Glass Industries, Pittsburg, Pa., LOF EZ-KOOL™ glasswhich is a green tinted glass of increased cerium oxide and iron oxidecontent, available from Libbey Owens Ford of Toledo, Ohio, or withequivalent specialized UV-absorbing glasses as described above inconnection with the electrochromic mirrors. Such specializedUV-absorbing glasses have a higher iron oxide content of within therange of about 0.2% to 0.9% by weight and/or a higher cerium oxidecontent of 0.2% to 0.9% by weight. Even higher iron oxide and/or ceriumoxide contents, such as 1% to 2% or more, can be contemplated, forapplications such as sunroofs, etc., where the dark tinting thataccompanies such high levels of iron oxide and/or cerium oxide may notbe product objectionable. For specialized UV absorbing glasses that havea high iron oxide content, it is desirable to maximize UV absorption bymaximizing the ferric (Fe III) ion content of the glass. Alternately, aspecialized UV absorbing glass of titanium dioxide content greater than0.2 weight percent or thereabouts can be used.

The exceptionally high near-IR reactances, and consequent beneficialclimate control when combined with an electrochromic window, attained byspecialized near-infrared reflectors is not achieved by standard low-Ecoatings such as semiducting oxides which are used in architecturalclimate control. This is illustrated in Table D and in the plots on thegraph of FIG. 41 which contrast the performance achieved using amultilayer stackes, such as the Cardinal Heat Mirror and the HM-55 filmdescribed above and incorporating an elemental metal thin film to theperformance attained with a low-E coating such as half-wave (1500angstroms) and full-wave (3000 angstroms) ITO.

TABLE D UV VISIBLE NEAR-IR SOLAR 300-400 nm 400-800 nm 800-2500 300-2500% T/% R % T/% R nm % T/% R nm % T/% R Half-Wave ITO 78%/13% 86%/10%64%/17% 77%/13% Full-Wave ITO 74%/16% 83%/12% 71%/17% 72%/14% CardinalHeat 53%/11% 83%/7%  42%/45% 65%/23% Mirror HM-55 36%/44% 52%/40%14%/81% 36%/57%

Whereas the ITO coating merely reflects less than 20% of thenear-infrared portion of the solar insolation in the 800-2500 nm region,the heat reflectors incorporating a thin elemental metal filmsignificantly reflect near-infrared radiation in this region with theCardinal Heat Mirror reflecting 45% solar near-infrared radiation andthe HM-55 film reflecting 81% in this region. The reason for this goodnear-infrared reluctance performance is illustrated in FIG. 41 whichplots percent reluctance versus wavelength in the 800-2500 nm region forhalf-wave ITO, full-wave ITO, Cardinal Heat Mirror, and HM-55. The thinelemental metal film based near-infrared reflectors are seen to rise inreluctance earlier and sharper in the near-infrared region than what isachieved with the semiconducting ITO coatings. Thus, combination of thinelemental metal-based reflectors with electrochromic windows moreclosely approaches the ideal performance for automotive glazing which isindependent control, via electrochromism, of visible light transmissionwhile simultaneously achieving maximal (ideally 100%) reluctance ofincoming near-infrared solar energy. In general, thin elementalmetal-based reflectors useful to achieve the objectives of thisinvention reflect at least about 30% of Air Mass 2 near-infrared solarenergy in the 800 nm to 2500 nm spectral range. The percent reluctanceof near-infrared solar energy for Air Mass 2 in the 800 nm to 2500 nmspectral range for silver thin elemental metal films ranging inthickness from about 60 angstroms to about 400 angstroms and depositedonto a glass substrate is plotted in FIG. 41A. As the graph shows, asilver film of at least about 60 angstroms, or thereabouts, thicknessreflects at least about 37% of Air Mass 2 near-infrared solar energy inthe 800 nm to 2500 nm spectral range. When a silver elemental thin filmof thickness ranging from about 60 angstroms to 400 angstroms issandwiched between two 180 angstroms titanium dioxide layers, with theresulting tri-layer stack itself deposited onto a glass substrate, thevariation of percent reluctance of Air Mass 2 near-infrared solar energyin the 800 nm to 2500 nm spectral range versus thickness of the silverfilm is given in FIG. 41B. Note that the titanium dioxide layers have ananti-reflecting effect in this spectral region. For this stack design, areflectivity in the 800-2500 nm spectral range for Air Mass 2 of atleast about 30% is achieved for a silver film of at least about 75angstroms or thereabouts.

FIG. 42 illustrates another embodiment 206 of the invention, theperformance of which is given in Table E.

TABLE E UV Attenuating, Near-IR Reflecting, Safety ProtectedElectrochromic Window UV VISIBLE NEAR-IR SOLAR 300-400 nm 400-600 nm600-2500 nm 300-2500 nm % T/% R % T/% R % T/% R % T/% R Bleached3.4%/10%  22%/26% 3.5%/29% 14%/27% Colored   0%/10% 3.4%/26% 2.6%/29% 3%/29% (1.0 volt)

Element 216 consists of panels 251, 252. Panel 252 is a blue-tinted,UV-absorbing specialized glass (3 mm thickness) available from FordGlass Company, Detroit, Mich., under the trademark SUNGLAS™ BLUE. Layers257 a and 257 b are blue-tinted plasticized polyvinylbutyral sheeting,each of sheet thickness 0.030″, available from E. I. duPont de Nemoursand Company of Wilmington, Del., under the trade name BUTACITE™ CobaltBlue B140 0547800. Layer 250 is a specialized near-infrared reflectoravailable from Southwall Corporation of Palo Alto, Calif., under thetrame name HM-55 film. Element 212 and panel 251 were coated on theirrespective surfaces 213 and 217 with a transparent conducting layer offull-wave indium tin oxide (ITO) of thickness approximately 3000angstoms and of 7 ohms/square or thereabouts sheet resistance. Theinterpane gap 218 between elements 212 and 216 was about 135 microns inthickness. The electrochromic medium 220 was an electrochemichromicsolution comprising:

0.035 M ethylviologen perchlorate 0.035 M5,10-dihydro-5,10-dimethylphenazine 5% wt/vol UVINUL ™ 400(2,4-dihydroxy-benzophenone)

dissolved in a solvent comprising 75% by volume 3-hydroxypropionitrileand 25% glutaronitrile. Coloration was achieved by applying 1 voltpotential across the electrochromic medium 220. Antilacerative layer 214is a two-layer composite comprising an inner tear-resistant sheet 214 aof plasticized polyvinylbutyral and an outer abrasion resistant layer214 b of polyester, and is marketed under the trademark BE 1028 by E. I.duPont, Wilmington, Del.

Layer 214 can also include silicone moieties chemically incorporated inthe anti-lacerative composite to prevent condensation and/or beading upof condensed water on the coated front surface 211 of element 212, inhigh humidity conditions thereby providing an anti-fogging, anti-mistingresult. A material found useful as anti-lacerative, anti-fogging layeris silicone impregnated polyurethane layer 214′ of sunroof/glazingembodiment 206′ shown in FIG. 42A. Layer 214′ is supplied under thetrade name CLARIFLEX™ by Saint-Cobain Vitrage of Paris, France. UVreducing additives such as those described above in connection with FIG.2 may also be incorporated in the anti-lacerative, anti-fogging layer toincrease the lifetime of the assembly. Alternately, element 212 may befashioned from conventional soda lime glass, UV reducing specializedglasses, or polymer plastics. It is also possible to utilize thin filmcoatings or UV reducing paints or lacquers on at least one surface offront element 212 when the anti-lacerative, anti-fogging layer isincorporated. Likewise, it is possible to apply a near-infraredreflector incorporating a thin elemental metal film to front surface 211of element 212.

The construction of FIG. 42 is particularly suited towards automotivesunroofs. As can be seen from Table E, transmission into the vehicleinterior is only 14% of the solar Air Mass 2 spectrum, even in thebleached state and this decreases to only 3% when the electrochromicmedium is colored. Note that visible transmission is 22% in the bleachedstate (acceptable in an automotive sunroof where the driver or vehicularoccupant will be viewing the outside bright sky through the sunroof)which decreases to only about 3.4% visible transmission when theelectrochromic medium is colored under 1.0 volt applied potential(desirable in that the driver or vehicular occupant perceives asignificant visible attenuation when the electrochromic sunroof dims andalso benefits from reduced solar glare). Further, and useful when bothdriving and parked, the total solar load transmitted into the carinterior is drastically reduced, particularly when the electrochromicmedium 220 is colored. Hence, the car can be parked for prolongedperiods in a sunny climate without such a sunroof contributingsignificantly to heat-buildup in the car interior. Note also from TableE that UV transmission through the complete assembly 206 is very smallwhen the device is bleached and is essentially eliminated when thedevice is colored. Such UV reduction is beneficial in avoidingdegradation of interior trim such as seats and carpets.

The appearance of assembly 206, when viewed from the side panel 252, isslightly but perceptively metallic-like in appearance whereas, whenviewed from the side of layer 214, the appearance is more blue-like intransmission. This is a benefit in that, since panel 252 is on theexterior of the vehicle, assembly 206 has a more metallic appearancewhile, to the vehicular occupant, assembly 206 operates from a partialblue tint to a dark blue tint. Thus, the driver and occupantssimultaneously benefit from a sense of privacy and from a sense ofuser-control over the sunroof tint. When dimming or dimmed, the changeperceived from the outside of the vehicle is much less than thatexperienced viewing from the car interior to the outside sky. Thus, theoutward appearance of the vehicle remains fairly constant (of benefit todesigners who desire a style and color match of the sunroof or otherglazing to the rest of the vehicle) while, simultaneously, the driver oroccupants perceive good value for their investment in acontrollable-tint glazing element. Also, the blue tint of the assembly,particularly in its fully or substantially bleached states, as seen intransmission from the interior vehicular cabin to the outside sky isparticularly advantageous in that such blue tint selectively andpreferably absorbs glare from the sun which is predominantly yellow incolor while simultaneously transmitting wavelengths in the blue andgreen region from 400 nm to 560 nm, and so preserving the blue, naturalcolor of the sky. Further, use of tinted means such as blue tintedglass, blue tinted polymer layers and blue dyes in the assembly allowuse of increased concentrations of UV stabilizers and absorbers whileavoiding the consumer undesirable yellow tint that usually accompaniessuch use of high concentrations of UV stabilizers and absorbers. Inwindow assemblies, excellent UV stabilization is particularly importantgiven that the electrochromic device will be exposed to intense UV solarradiation, typically while in its colored state.

Also, for additional scatter protection and safety, in any of the abovedisclosed mirror assembly embodiments, any of the glass panels of theassemblies could be formed from safety glass that has been temperedand/or toughened by conventional means including thermal, contact andchemical tempering. Also, such tempered, safety glass can be blue orgreen tinted to provide the advantages described above. In addition,layer 214 provides occupant protection against injury due to scatteredglass or lacerative contact with broken shards and prevents immediateoccupant and interior trim contact with the solvents and chemicals usedin electrochromic medium 220. Likewise, and particularly forapplications such as a sunroof, sun visor, or shade band where sun glarereduction, good shading efficiency, and good thermal insulationperformance is desirable, at least one of elements 212, 216, 251 and 252can be formed from architectural glass such as SOLARBRONZE™, a bronzetinted glass; SOLARGRAY™, a gray tinted glass; GRAYLITE™, a dark graytinted glass; and SOLEX™, a green tinted glass; all available fromPittsburgh Plate Glass Industries of Pittsburgh, Pa.; SUNGLAS™Gray, agray tinted glass; and SUNGLAS™ bronze, a bronze tinted glass; availablefrom Ford Glass Company, Detroit, Mich.; and with E-Z-EYE™, a greentinted glass; available from Libby Ownes Ford of Toledo, Ohio. Further,elements 212, 216, 251 and 252 can be coated with low-emittancemonolithic architectural coatings such as SUNGATE™ 100, a low emittance,high transmittance coatings available from Pittsburgh Plate GlassIndustries of Pittsburgh, Pa.; and SUNGLAS™ HR, a low emittance, hightransmittance coating available from Ford Glass Company, Detroit, Mich.Also, ECLIPSE™, a pyrolytic Low-E coating available from Libby OwensFord of Toledo, Ohio can be used. Further, elements 212, 216, 251 and252 can be coated with vacuum deposited architectural coatings such asSOLARBAN™ available from Pittsburgh Plate Glass Industries ofPittsburgh, Pa., or can be coated with KOOLOF™, a solar control coatingavailable from Libby Ownes Ford of Toledo, Ohio.

Further, perimetric or perimeter coatings and darkened/color matchedseals, as described in U.S. Pat. No. 5,066,112, entitled PERIMETERCOATED, ELECTRO-OPTIC MIRROR, invented by Niall R. Lynam, the disclosureof which is hereby incorporated by reference herein, can be applied towindow glazing constructions such as shown in FIGS. 37, 40 and 43. Forexample perimetric or perimeter coatings, 310 and 311 of FIG. 43, of aconductive black frit or paint, can be applied around the perimeter ofsurface layers 213 a and 217 a so as to hide from view the seal 229 andthe connection of electrical leads 22, 24 to layers 213 a, 217 a. Asuitable material is ENGLEHARD SC 6002 (# 6082), a platinum/palladiumconductive ink available from Englehard Corporation of Iselin, N.J.Also, seal 229 can be color matched to any bezels, gaskets,encapsulates, or vehicular body moldings used to fix the electrochromicwindow assembly into a vehicle. For example, carbon black, in anonconducting form, could be added to seal 229 in order to render itcolor matched to any black or dark rubber or plastic encapsulation meansused to secure the electrochromic assembly into the vehicle.Alternately, perimetric or perimeter coatings 410, 420, as shown by thedashed lines on FIG. 43, and formed from, for example, a frit materialsuch as DRAKENFELD™ black enamel 24-1729 available from DrakenfeldColors of Wilmington, Pa., can be used to obscure from view theseal/electrical means used in the assembly.

While several forms of the invention have been shown and described,other forms will now be apparent to those skilled in the art. Therefore,it will be understood that the embodiments shown in the drawings anddescribed above are merely for illustrative purposes, and are notintended to limit the scope of the invention which is defined by theclaims which follow.

What is claimed is:
 1. A reduced ultraviolet transmitting,electrochromic vehicular glazing assembly adapted for mounting in avehicle having an interior and an exterior, said assembly comprising:first and second spaced optically transparent panels, said first panellocated closest to said exterior of said vehicle when said assembly ismounted in said vehicle and said second panel located closest to saidinterior of said vehicle when said assembly is mounted in said vehicle;said first and said second panels each having a front surface and anopposing rear surface, said rear surface of said first panel facing andspaced from said front surface of said second panel defining a spacebetween said first and second panels, said rear surface of said firstpanel and said front surface of said second panel coated with atransparent electrical conductor; an electrochromic medium disposed insaid space whose light transmittance is variable upon the application ofan electric field thereto; ultraviolet radiation reducing meansincorporated in said assembly for reducing ultraviolet radiationtransmission through said assembly; and wherein said ultravioletreducing means comprises at least one of an ultraviolet absorber, andultraviolet absorbing polymer and an ultraviolet absorbing glass.
 2. Thevehicular glazing assembly of claim 1 wherein said glazing assemblycomprises a vehicle window.
 3. The vehicular glazing assembly of claim 1wherein said glazing assembly comprises a vehicle sunroof.
 4. Thevehicular glazing assembly of claim 1 wherein said glazing assemblycomprises a vehicle sun visor.
 5. The vehicular glazing assembly ofclaim 1 wherein said glazing assembly comprises a vehicle shade band. 6.The vehicular glazing assembly of claim 1 wherein at least one of saidfirst and second panels comprises a tempered, safety glass panel.
 7. Thevehicular glazing assembly of claim 6 wherein each of said first andsecond panels comprises a tempered, safety glass panel.
 8. The vehicularglazing assembly of claim 1 wherein at least said panel comprises atempered, safety glass panel.
 9. The vehicular glazing assembly of claim1 wherein at least one of said first and second panels comprises atinted glass panel.
 10. The vehicular glazing assembly of claim 9wherein said tinted glass panel has a tint selected from the groupconsisting of a blue tint, a green tint, a blue/green tint, a bronzetint and a gray tint.
 11. The vehicular glazing assembly of claim 1including polymeric antilacerative layer disposed on said rear surfaceof said second panel for preventing lacerative injuries should saidsecond panel crack or break; said antilacerative layer comprising asingle-layer polymer film.
 12. The vehicular glazing assembly of claim11 wherein said single-layer polymer film comprises polyurethane. 13.The vehicular glazing assembly of claim 1 including a polymericantilacerative layer disposed on said rear surface of said second panelfor preventing lacerative injuries should said second panel crack orbreak; said antilacerative layer comprising a two-layer polymer film.14. The vehicular glazing assembly of claim 13 wherein one layer of saidtwo-layer polymer film comprises plasticized polyvinylbutyral.
 15. Thevehicular glazing assembly of claim 14 wherein the other layer of saidtwo-layer polymer film comprises polyester and wherein saidpolyvinylbutyral layer is disposed between said polyester layer and saidrear surface of said second panel.
 16. The vehicular glazing assembly ofclaim 1 wherein said transparent conductor comprises one of indium tinoxide, doped tin oxide and doped zinc oxide.
 17. The vehicular glazingassembly of claim 1 wherein at least one of said first and second panelscomprises a specialized glass transmitting in the visible portion of theelectromagnetic spectrum and having reduced transmission in theultraviolet portion of the electromagnetic spectrum.
 18. The vehicularglazing assembly of claim 1 wherein at least said first panel comprisesa specialized glass transmitting in the visible portion of theelectromagnetic spectrum and having reduced transmission in theultraviolet portion of the electromagnetic spectrum.
 19. The vehicularglazing assembly of claim 18 wherein at least said first panel comprisesa tempered, safety glass panel.
 20. The vehicular glazing assembly ofclaim 19 wherein at least said first panel comprises a glass panel bentto a compound curvature.
 21. The vehicular glazing assembly of claim 1wherein said assembly incorporates spectrally absorbing means forabsorbing more light in those regions of the visible spectrum from about560 nanometers to about 780 nanometers than is absorbed in those regionsof the visible spectrum from about 400 nanometers to about 560nanometers.
 22. The vehicular glazing assembly of claim 1 wherein saidultraviolet reducing means comprises an additive for absorbing, blockingand/or screening ultraviolet radiation.
 23. The vehicular glazingassembly of claim 22 wherein said additive is selected from the groupconsisting of benzophenones, cinnamic acid derivatives, esters ofbenzoin acids, salicyclic acid, terephthalic and isophthalic acids withresorcinal and phenols, pentamethyl piperidine derivatives, salicylates,benzotriazoles, cyanoacrylates, benzilidenes, malonates, hinderedamines, organo-nickel complexes, nickel chelates and oxalanilides. 24.The vehicular glazing assembly of claim 22 wherein said additivecomprises a benzophenone.
 25. The vehicular glazing assembly of claim 22wherein said additive comprises a benzotriazole.
 26. The vehicularglazing assembly of claim 22 wherein said additive comprises acyanoacrylate.
 27. The vehicular glazing assembly of claim 22 whereinsaid electrochromic medium includes said additive.
 28. The vehicularglazing assembly of claim 22 including a polymeric antilacerative layerdisposed on said rear surface of said second panel for preventinglacerative injuries should said second panel crack or break; saidantilacerative layer including said additive.
 29. The vehicular glazingassembly of claim 1 wherein said assembly includes near-infraredradiation transmission reducing means.
 30. The vehicular glazingassembly of claim 29 including a polymeric antilacerative layer disposedon said rear surface of said second panel for preventing lacerativeinjuries should said second panel crack or break; said near-infraredradiation transmission reducing means are located on at least one ofsaid first panel, said second panel and said antilacerative layer. 31.The vehicular glazing assembly of claim 30 wherein said near-infraredradiation transmission reducing means comprises a near-infraredreflector deposited onto said antilacerative layer.
 32. The vehicularglazing assembly of claim 1 including a polymeric antilacerative layerdisposed on said rear surface of said second panel for preventinglacerative injuries should said second panel crack or break; saidantilacerative layer comprising an anti-fogging antilacerative layer.